installation interruptus

[John Knight]

 Installing ydl 4.0 as the only system on an imac rev a. I got to
insert cd #2.  Process could not read cd. I tried a new burn of cd #2.
Still no luck. Error message said a part of open office was corupted.
I did alt f3 and shutdown.  My plan was to restart the installation
process in custom mode and skip corrupted files.

The bad news is that I cannot boot into  cd#1 by holding down "c". 
The process of installation wiped out the Imac bootstrap. What can I
do?

I am a X86 type and do not know any macisms :{

tia 
John