Sun Blade 150 install - fails on reboot, fails to configure X?

[amacater@galactic.demon.co.uk (Andrew M.A. Cater)]

Just been troubleshooting an install at work for a colleague who
previously posted to the list about troubles with CD ROM on Sun
Blade.

Finding the right net install image, he can install Debian and then
add the normal CD ROMS to his apt sources. Installing a complete
workstation then works - or appears to.

Reboot fails: SILO has the wrong arguments?  The kernel boots and
then fails to find the initrd. I've had this problem before -
if anyone can remember the magic incantation to feed SILO so that
we can get back into our newly installed system, I'd be grateful :)

My colleague did manage to install a basic system sometime previously
- when I tried to configure X, all I could get was "no usable video modes
  found" or some such. The card is an ATI Rage of some description -
  I'm not at work now so can't check exactly - does anyone have a
  working XF86Config. System running Sarge i.e. Stable apart from
  needing the netinst disk to bootstrap it.

  Andy