Hi guys!! We have a few new HP machines here at my UNI. I have found that if the bios is set to "removable drvices" it will try to boot from the usb stick!! this was the default setting on ours "this detects for floppy disk's too".
I am 99.9% sure it can be done on most new systems.
If i can help you anymore let me know I i will do a little testing here as I haven't booted from one yet, but had the error msg saying non boot media detected, removed my memory stick and she booted from the hdd