How to force stage2 from the NFS repository instead of the boot.iso?

[G.Wolfe Woodbury]

My testbed machine's DVD is getting a little flakey and it will be a
while before I can replace it. It boots anaconda fine, but start to have
trouble (as it warms up) with the stage2.img file off of the CD.

As I Understand It (AIUI) there should be a way to tell the boot process
to fetch stage2 from an NFS mounted local repository, but I haven't been
able to figure it out by myself.

Would someone post an explanation of the stg2= stuff?  Where it goes and
how to specify the NFS location correctly?

Thanks.

-- 
G. Wolfe Woodbury