VPN Masquerading support on Kernel 2.4

Hi:
There was a patch provided for 2.2.x versions of the Linux kernel to assist with VPN masquerading. (it works with IPCHAINS)
Is there such a patch available for kernel 2.4.x ?
If not is it possible to setup iptables to allow
masquerdaing with VPN ?

Thanks much

Ramdev/-