First, this works reliably only with an Intel Mac.
Second, even if you have a reliable DVD drive, you might want to set this up if you frequently reinstall the OS, as I found it installs faster than the DVD and you're never going to scratch or scuff up a flash drive.
What you'll need:
- Leopard install DVD or a DMG of an install DVD
- 8Gb flash drive (4Gb isn't enough for Leopard, though it is for Tiger)
- Bombich Software's Carbon Copy Cloner, version 3.1 or newer
- About an hour
If you already have a DMG of a complete Leopard install DVD, you can skip the following section.
Put the Leopard DVD in, start Disk Utility, and make a DMG of it. This will take about 20 minutes, possibly less.
Plug in your flash drive, and repartition it as a single partition, and under "options," set it for GUID, not MBR, so that it can be used to boot an Intel machine. Call the drive something simple, like maybe "leopard" or "boot."
Close Disk Utility, and start Carbon Copy Cloner.
For your source, use the DMG you just created. For the destination, use your flash drive, and select "erase destination." CCC will whine about the fact that the DMG doesn't have a "users" folder and will claim it won't boot because of this, but ignore it. You're smarter. Start the clone.
About 20 minutes later, you should have your flash drive all loaded up with the Leopard installer. Exit everything, eject the DVD and restart the machine. Hold down option while you're booting, and select the flash drive you just created. If it isn't listed as an available, you fouled something up, so go back and do it over. Assuming it's listed as available, go ahead and boot from it, and the installer will start.
If you want to modify or trim down your Leopard installation, you can actually get it down to where it'll fit on a single DVD.
To do this, start Disk Utility. Select New Image up at the top. IMPORTANT: set the options on this new image so that its partition type is "sparse," in the lower dropdown selector. Set its size to be a dual-layer DVD (8.something Gb). Call it something simple.
Load up the full-size DMG,click once on the image (not the mounted disk icon) and in the menus, select "Scan image for restore." Once it has scanned, click on the Restore tab. Use the image file as your source and the mounted disk icon of the new image as the destination. Check off "erase destination," and click "restore."
You should end up with a new image mounted which is fully read-write. Thus, you can take unneeded stuff out of it.
Things you can chuck over the side:
- the Instructions folder
- The XCode tools folder
- Unneeded language translations
- unneeded printer drivers
Now, the thing is, the folder in which these last few things are located is hidden, but you can get it to display itself pretty easily. Open up a Terminal window and issue the command open /Volumes/whateveryoucalledthenewimage/System and a new Finder window will open up with the folder ready for you to trash. Just remove whatever printer drivers and additional languages you don't need. No normal person owns a Brother or Fuji Xerox printer, folks. Keep the Gutenprint drivers if you think you have space. The Epson folder is nearly a gigabyte by itself.
Do not be tempted to remove other stuff, or your installer will puke.
Once you've removed everything you want to remove, unmount the sparse image file and remount it. If you want to use this to set up your flash drive, start Carbon Copy Cloner, and use that mounted drive as the source for your clone over the flash drive. No, it won't fit on a 4Gb.
If you want to fit it on a single DVD, it's a little trickier. Open Disk Utility, scan the image for restore, and then put a blank DVD in. Click the image and hit Burn. It should write a bootable, usable DVD for you.