Format of f2 and f3 files?

I've got my customized version all ready to be burned to CD except for one small problem...

I added the hostname cheatcode (as described elsewhere in this forum). I want to add that to the one of the f2 or f3 file. I also want to add another file (f4 I'd guess) to describe some recommended stuff.

Best I could find about these files was here
http://www.knoppix.net/forum/viewtopic.php?t=22798
which to be honest didn't help me much.

Can someone try to enlighten me further?

Thanks in advance.