This guide is currently Leopard-only! Don't even bother with any of these instructions on Snow Leopard, they won't work!

Advanced 3: Customizing the Mac OS X Leopard Installer

As with most other guides, this will require a copy of Mac OS X Leopard (10.5) in order to function. Also, this guide assumes that you have already created a bootable USB Installer drive as described in Method 1, or in the Old methods.

*Note: Since some people have been using my guide for nefarious purposes, such as this thread on MyDellMini, I will point you to my Legality article and hope that you will think before hacking an OEM disc.*

Open for Modification

1) We're going to modify one file on the drive. Since the containing folder is hidden by default, we will use Terminal to access the folder. With your USB drive plugged in, open Terminal and enter the following command:
open /Volumes/OSXDVD/System/Installation/Packages

2) Copy the file OSInstall.mpkg to the root of you hard drive. Assuming your hard drive is called Macintosh HD, you would enter the following command into the Terminal:
cd /Volumes/"Macintosh HD"
*Note: Remember to replace "Macintosh HD" with the name of your hard drive. If the name consists of a single word, quotations are not needed, but if it does have a space, you will need to place quotation marks around the name, as in the example.*
*It is recommended that you make a backup copy of the OSInstall.mpkg file, in case everything goes wrong. You can do this simply by right-clicking the file and selecting Duplicate. This will create another file called "OSInstall.mpkg copy".*

3) Now enter the following command into Terminal:
xar -x -f ./OSInstall.mpkg
You should now see two new files/folders appear on your hard drive. These files are called Resources and Distribution. It is the Distribution file we are most interested in. Right-click (or control+click for one button mice) on the file and highlight "Open With" and then select TextEdit. (If TextEdit does not already appear in this list, select "Other..." and then scroll through the list of Applications to select it.)

Modifying Distribution

I will explain what these modifications entail as we progress along.

4) The first line we want to modify is very close to the top. The line is as follows:
<options
eraseOptionAvailable='true'
hostArchitectures='ppc,i386'
allow-external-scripts='yes'
/>
The first line to delete is "eraseOptionAvailable='true'" so just get rid of it. When that is completed, that part should now look like this:
<options
hostArchitectures='ppc,i386'
allow-external-scripts='yes'
/>

*This line is what tells the Installer to only install Mac OS X to a drive with a GUID partition scheme. By deleting this line, we enable the Installer to install to both GUID and MBR (Master Boot Record) schemes. MBR is ideal for smaller SSD's and multi-boot configurations. It does not automatically create hidden EFI partitions, and is automatically installable by Windows and older operating systems.*

5) Next, we want to scroll down to this section:
<choice
id="EssentialSystemSoftware"
title="EssentialSystemSoftware_title"
description="EssentialSystemSoftware_description"
start_enabled="false"
>
</choice>
Begin replacing every entry that says "false" with "true", including the one above. It will look similar to this:
<choice
id="EssentialSystemSoftware"
title="EssentialSystemSoftware_title"
description="EssentialSystemSoftware_description"
start_enabled="true"
>
</choice>

Continue replacing these values until the Migration Assistant section, which look like this once you have completed the process:

<choice
id="MigrationAssistant"
start_visible="true"
start_selected="upgrade_allowed()"
>
<pkg-ref id="com.apple.pkg.MigrationAssistant"/>
</choice>

*This modification tells the Installer to allow the user to select even more components to install (or not to install) during the Customization portion of the installation process. This becomes important especially for those attempting an install on an 8 GB SSD, since this will allow them to free up more space for the installation to actually happen. This will be described more later.*

6) Once you are done with these modifications, save the changes, and return to the Terminal window. Enter this new command:
xar -c -f OSInstall.mpkg *
Hopefully you did not close the Finder window that showed the Packages folder on your USB drive. Copy the OSInstall.mpkg file from your hard drive back to the USB drive. Go ahead and replace the file. Now you can close all related windows and eject the USB drive.

*Note: Some people have been having problems with this step, which I have been unable to reproduce as of yet. I was sent an e-mail by fellow MyDellMini forum member mostro, in which they detail one alternate way to make this step work. Quotation following.*

It has trouble with this command. It just sits there with a blinking cursor, indefinitely after entering it. If I remove the asterisk at the end, it complains "No file to operate on." But with the star, it sits forever and never finishes. If I delete the OSInstall.mpkg file and run that command, it will recreate it as a 0k file and never does anything to it.
I assume, you meant to have this be in a separate folder at the root of the HD, not right at the root of the HD, and so the * would include everything in that dir. So I just did this instead:

xar -c -f OSInstall.mpkg Distribution Resources/

and that worked, it created the file with 860KB (compared to the original at 804KB), so I figure it worked.

Running the Modified Installer

Now that the Installer has been modified, we can run it like normal, but with a few new advantages: Master Boot Record functionality, and reduced installation size due to more removable components.

A) Master Boot Record

Now in Disk Utility, you are able to partition a drive with the MBR option. Before the modification, the Installer would have placed a red stop icon on the partition, no matter what format it was. This is helpful 1) if you are going to install another operating system(s) later and want to partition your drives using Disk Utility in preparation for those installs, or 2) you have installed the alternate operating system(s) previously and your SSD has been patitioned with the MBR scheme already.

MBR also has the advantage of reducing free space waste by eliminating the (rather useless) EFI partitions that are inherent to GUID schemes.

B) Removable Components

The other major change is now you will be able to modify the top entry of the Customization window, "Essential System Software". There are actually some components in this group that are not necessary, but Apple felt like making them mandatory for installation. The main problem with modifying these settings is that there are a many things that absolutely need to be installed or your OS may not boot, much less function correctly. Below is a list of all the components included in this group, along with sizes (for identification), a brief description, and whether or not they can be removed.

You may also notice two entries not in the Essential System Software group that have no names, make sure that these are still selected. It is unclear what they are, but they should be maintained so that the OS does not fail.


Be careful with how you use these features. This guide was created using a 10.5.6 disc, so if you have differing results with how the Installer functions after this alteration, let me know. And if anyone knows any other awesome modifications for the Installers, Contact me.

mechdrew Advanced 3 Version 3.02