Port forwrading help?

Folks:

I'm trying to get a jabber server running on my linux system so that it
will listen on port 5222 (the default) and 80.

Can anyone recommend a way to forward port 80 on a particular IP to port
5222 on the same IP?  I'd also like to have the source IP show up
correctly (i.e., the actual source IP instead of the IP where the
traffic is being forwarded from).

I've tried using portfwd, but it seems to want to listen on all IP's all
the time.

I found a small utility that would listen on a specific IP / port and
forward the traffic to another IP / port ... but the source IP is where
the forwarding is taking place.

I found some references to using iptables to forward traffic ... but I
haven't been able to make it work.  Parms mentioned in the document
aren't valid on my version of iptables.

FWIW: I'm using Fedora Core 4.

Thanks!

david