initrd kernels and mklinux booter

[Rich Johnson <rjohnson@dogstar-interactive.com>]

I've a couple of nubus powermacs currently running stock 2.4.21 with 
the mkLinux booter.  I'd like to bring them up to a 2.6 series kernel.

I've got two-1/2 questions:
- Is there a stock kernel I can use or do I have to roll my own?
- Is initrd supported?  If so, what boot options ("mach_options") do I 
specify?

Thanks!