Why do u need NAT ? U want them connected to external world or any other specific reason ?
I have worked only on RedHat . But still u can use the ipchains utility to accomplish NATting .
Search for ipchains tutorial on www.google.com
and also read the howto on www.linuxdoc.org.
basically for NATting u also need to do ipforwarding.
Maybe if u give me more details i can help u out.