It would help if you would tell us which unix you are using. The only usbkvm manpage I find is
here, and when I read the man page, I see:
open("/dev/kbd", O_RDWR)
and I would expect this module to be autopushed anyway. Be sure that you're open the right device. And run autopush on that device to be sure that the module really needs an explicit push.
I sorta doubt that a keyboard module will handle a bar code reader anyway. But I've never worked with this stuff, so who knows...