sry, but I don't use any usb devices, so I'm not on top of things as far as which modules are necessary. This should give you a starting point. For more specific information (such as how to compile a kernel try to google for info):
http://rtfm.dyndns.info/tips/2002/02/01/44.shtml
If you want this explained in a little further detail, then I guess we could keep on chit chatting.
; )
So as it said, you have 3 modules to choose from:
usb-ohci or usb-uhci or uhci
I'm going to hope that MDK compiled its kernel with this stuff.
So try to modprobe all the modules it listed. Maybe we'll get lucky. If not, we'll have to recompile.
Oh yeah...I recommend for the time being to boot the computer and press ctrl-alt-F1 when you get to the graphical login. This will put you into a console login, and it will be easier for you to move around.