it needs the plan 9 c compiler, but
it's not actually the kernel that's at fault here: aux/vga is
a user-level program, and it's in the bzip'd file
system on the diskette.    i've put a modified diskette image that
might work on http://www.vitanuova.com/ndisk.gz;
you'll need to replace plan9.ini by the one you've been using.