Is it possible to boot a Toshiba Tecra A2 from a USB flash drive?
BIOS shows no boot option for USB. I haven't yet found any way to do it, but I might be missing some option.
I don't know which BIOS version is yours, but did you try to change your BIOS settings? I believe you can enter in your notebook's setup by pressing F1 after it's turned on. Then check "boot devices" and see if "USB" is taking precedence from "Hard Disk" and other peripherals.
It seems like the Tohshiba Tecra A2's motherboard does not support booting from USB devices. You may however circumvent this by installing a boot manager with USB support on a CD and booting from this medium instead.
One such boot manager, Plop, can be downloaded here.
Burn the .iso to a disc, boot from that and a menu will appear. Select 'USB' and voila.