said by mfwizard:F2 is actually the key to get to the BIOS on the Sony. And, you have to be quick with it! USB boot is not an option.
I would not be surprised at all that USB isn't an option, but did you confirm that by pulling up the boot menu? (not entering the bios itself) F12 is the standard, though I've seen some use F10.
On this laptop, I can't set a USB drive as a boot option in the bios, but I can press F12 to get the boot menu, select it, and then boot to it.