> 
> So, how do I get back at the boot prom from a HP mode boot?
> 

Quite simple, provided you are a bit adventurous or deperated and try to bang
at the keyboard when it seems to be stuck in 'search mode'... Pressing the 'C'
key during search mode 'slowly' pops up a menu containing also a topic 'boot
mode'.There, you can permanently or temporarily switch the boot mode back to
Domain/OS.

Yes, it is very hidden...     
Michael