Well I tried one flash drive and it wouldn't read, so I switched drives and pressed UP + L2 and the program seemed to freeze. I let it sit for a few minutes but still no response.
I'll plug in an actual hard drive later to see if I can get better results.
What I really need to know is what .ELF program should I be booting, the USBAdvance or ULaunchelf?
I can't really know what I'm doing wrong until I've got at least one thing right. Thanks.