Ouch, keyboard, for video games? that reminds me of jumping on a bike with no seat... Honestly use a n64 controller, its dirt cheep?
but ok, if you must I would do this..
C-buttons use num pad. 8,6,2,4
use the up arrow for B and right arrow for A or ( Left arrow for B and up arrow for a )
Enter is a good start button and space is a good trigger
Shifts would work good for shoulder buttons
a,w,d,x for moment.
since the dirrection are never really used I would put them on insert(left) pgUp ( right) end ( down) s.lock ( up)
But really its up you how you feel its best for you, after all a keyboard? really?