Password protect kickstart server

[thomas.moersch at sasktel.sk.ca]

Hi,
I am installing servers using the kickstart process.  Unfortunately anybody
on our company's network can install from this server via nfs.  All they
need it a bootable floppy disk set or a bootable cd and off they go.
Here is the command they need top use from the boot prompt:
      linux ks=nfs:servername:/source/ks/clientname.ks

I want to restrict this if possible through the use of a password.  I would
hate to go as far as turning the network share on only when I need it or to
restrict it by client ip.
Are there better ways?

Thanks in advance.

Thomas