I have made great progress on creating a UEFI compatible, linux-based, USB boot disk. Basically, I added UEFI support for SLAX linux. Now, it supports BIOS, 32-bit UEFI, and 64-bit UEFI, on both 32-bit and 64-bit CPUs.
Check out the archive here:
UEFI boot support works just by copying the files to a Flash drive, for BIOS boot support, you'll need to run a command from an admin shell. It's almost midnight now, and I don't recall the exact command needed. Remind me in the morning to check on that.