The Neoware CA2 has a conventional Phoenix AwardBIOS that is entered by hitting the DEL key whilst the unit powers up. The options for a Boot device are:
No sign of any USB option.
I've connected a CDROM drive to the IDE connector and booted Puppy Linux V4.2 without any problems.
I've also connected a 2.5" drive running Tinycore V2.7. The first time I booted this there was an apparent problem, but subsequent boots have been fine so I'm not too sure what the problem was.