There are two simpler ways if - like me - all you need is to temporarily boot with an emergency USB flash drive (thumb stick) so you can repartition, repair, or reinstall on your regular drive(s)/volume(s). One of these two ways may very well work for you:

1.) Many users report that the Startup Manager works for them (holding down the Option key during startup). (see: http://hints.macworld.com/article.php?story=20061017084322177)

I was not so lucky on my iBook G4, but I found that a venerable trick from classic Mac days worked just fine for me:

2.) During start-up, hold down simultaneously Command-Option-Shift-Delete. This makes the Mac skip the default boot device setting and scan for an alternate boot device. Be prepared for an agonizingly slow boot through early version USB ports. Your vintage OS-X-Mac may seem hung for a while but is actually just watching paint dry and will eventually move on. ;-)

If neither of these works, read my P.S. below.

Enjoy. :-)


P.S.: BEWARE: Disk Utility, by default, sets up a flash drive with the Fdisk_partition_scheme (at least in my Tiger version). This makes booting from that flash drive on a Mac (or only PPC Mac?) impossible despite of the Mac OS Extended file system etc. which you may have put on that flash drive. So, when you prep the flash drive, select the drive itself (not its volume) in Disk Utility, click on partition, name the partition (Mac OS Extended should be the selected file system by default - journaled is probably best), and - VERY IMPORTANT - click on that inconspicuous "Options" button to switch the partition type to Apple_partition_scheme. Also, if you want to try your hand on the Open Firmware scripting described in the preceding discussion, "boot" just boots this one time, whereas the "setenv" stuff gets to stay in the firmware until you change it back or reset the firmware, even after shutting down.