port forwarding

[Wakan]

I need to enable port forwarding to let a machine
internal to the lan to run emule.
I found some example n the list, but it doesn't work.
I'm running a debian woody/ipmasq router/firewall on 2.4.18-bf2.4 kernel.
this is the version:
router:~# apt-cache policy ipmasq
ipmasq:
  Installed: 3.5.10d
  Candidate: 3.5.10d
someone can help me?