If you don't have a USB disk, you can use any sort of media that the PS3 can read - CDROM, DVD, compact flash, etc. Just make sure that the file is called /PS3/otheros/otheros.bld.
2. Plug the USB disk into your PS3, and navigate to System -> System Settings -> Install Other OS. The PS3 should find the new file on the USB disk, and install it.
3. To boot with petitboot, just set your default operating system to "Other OS" (System -> System Settings -> Set Default OS), and reboot.
Using Petitboot When petitboot starts, it will try to find existing Linux installations, by looking for /etc/kboot.conf, /etc/yaboot.conf or /boot/petitboot.conf files on any storage device connected to the system. Each discovered device will appear on the left-hand pane of the screen, and bootable options appear on the right.
You can navigate the boot options with the arrow keys (if you have a USB keyboard connected), or the D-Pad on the PS3 controller. If you're using a PS3 controller, you will need to have it connected via the cable; wireless controllers aren't supported (yet!).
If you only have a blank screen with no device icons, then petitboot has not found any bootable options. You can flip to a text console (using Alt+F1) to investigate.
The keys available are pictured below.
Petitboot Console If you're using the petitboot console (either by hitting Alt+F1, or logging-in over the network), you have a fairly standard Linux system available. Some notes:
Discovered storage devices are mounted under /var/tmp/mnt, named by their device. For example, /dev/ps3da1 is mounted at /var/tmp/mnt/ps3da1.
To boot a kernel, use kexec: kexec -f --append="root=/dev/ps3da1" /var/tmp/mnt/ps3da1/boot/vmlinux .
Reverting to the Standard PS3 Software If you'd like to revert to the standard PS3 behaviour (ie, the PS3 boots directly to gameos), then you can just do a reset of the PS3:
1. Turn the ps3 off
2. Hold down the power button until you get a second set of beeps
The ps3 boot sequence will now be back at the factory default.
Stay tuned for more PS3 Hacks and PS3 CFW news, follow us on Twitter and be sure to drop by the PS3 Hacks and PS3 Custom Firmware Forums for the latest PlayStation 3 scene updates and homebrew releases!
WOW, this bootloader is simply amazing, I tried it and it worked fine, but still a little unstable, but I wouldn't recomend using it until it has most of the bugs worked out. When the major bugs are gone this should cost $15 to download because of ease of use.