8042 KBC firmware

I'm working on a x86 virtualization project and having a hard time with 
emulating the PC keyboard interface correctly. The problem is that the 
8042-based keyboard controller interface is reasonably well documented, 
the 8042 chip itself is well documented, the AT and PS/2 keyboards are 
well documented, but no one seems to say what exactly the 8042 firmware 
does.

Does anyone here know where I might obtain a ROM dump of a PC 8042-based 
keyboard controller? Doesn't really matter how old, though something 
with PS/2 mouse support would be best. Commented 8042 source code would 
of course be even better, but that's probably not likely...

Thanks in advance for any info.