Port redirection to bypass restrictions... :-/

Hi!

I'm trying to bypass a firewall using Linux as a router. The details
are:

*I have a public IP and http access is NOT blocked on the computer
where the blocked traffic originates.
*SMTP and POP are blocked by a firewall.

At my disposal I have on a different network:

*A Fedora Linux server with a private IP behind a Cisco on
under my control. (192.168.0.x)
*A Cisco router acting as a firewall/Gateway for the 192.168.0.x
network with a public IP address.

Ultimately I would like to be able to use outlook instead of using the
crappy web interface. To do this I was hoping to direct the SMTP an POP
traffic to the Linux machine or the Cisco that are on a different
network as HTTP traffic and have the Cisco or Linux machine do a port
translation and forward on the stream that arrives from the fire walled
machine with outlook on port 80 to the real POP and SMTP server on the
real ports.

I think only certain ports are blocked so I can use other ports but not
25 and 110.

I know it would be accomplished with IPTABLES but it's a little
confusing. Well ok, its very confusing. If I could just get some one to
give me an example of how to go about this because all examples I've
found use NAT and assume that either the destination or source IP is
inside a private network. In this case they are both public addresses
and I only need to use the Linux server or Cisco to translate the ports
to go around the firewall.

Oh, and I can forward any traffic from the public IP on the Cisco to
the Linux machine with the ip nat inside source static command.

Any thoughts? Thanks In advance guys an gals!