I've just got iptables etc. going on a 2.4 kernel, though not on the VMware
box. The info you're looking for is not VMware-specific. You'll do better
looking on the general Linux source sites, especially given the relative
newness of the 2.4 kernel.
Start with: http://netfilter.kernelnotes.org/ -- has links to relevant 2.4
networking links. Nat-specific HOWTO for 2.4 is at
http://netfilter.kernelnotes.org/unreliable-guides/NAT-HOWTO/index.html .
Good luck!
- Bob