Processor Module for PB 550c

I know this is a long shot but I came across a PowerBook
550c that  
has a PowerPC upgrade card installed. The original processor
module  
is not available. Does anyone have any idea if it is even
possible to  
get a 68040 processor back in there somehow? I want to run
NetBSD on  
it but a PowerPC upgrade card will not work. Thanks for the
time.

Bryan