[K12OSN] booting imac

[Gavin Chester]

I know nothing about imacs but was just given one with a dead hard drive
to play with.  I thought: what better use for it than as a thin client
on K12ltsp :-)  I can't find any info on booting these as a thin client,
other than I read that it is being done.  For example, is this thing
going to network/pxe boot with the hard drive dead/removed? 

Supplementary question ;-)
I have found howtos on installing linux on imacs, and I was surprised to
find that the drive in this imac is a standard 6GB IDE, so I popped an
identical drive in and tried to get an install happening. Seems to be a
'no-show' without the mac CDs to do something with the 'openfirmware'.
IOW, I can't get the thing to boot from my linux install CDs.  I read of
the trick of using the key combo of 'apple+alt+o+f', but that made no
difference to me seeing a mac icon flashing alternately with a question
mark.  Could someone please point me to a howto on booting an imac to
install linux with ONLY a _blank_ replacement drive?  Thanks. 

Gavin