ipchains redirection

[Oki DZ <litbang@haltek.telkom.net.id>]

Hi,

I have two modems than can be connected to the Internet. Since there can
be only one default route, I'd like to split the traffic by protocol
types; eg: http on one line, ftp + smtp on another line. I think ipchains
(-j REDIRECT) can do that. Unfortunately, I couldn't find nice examples on
using ipchains redirection. Even if splitting the traffic can only be done
on certain protocols and on particular hosts, that would be fine; other
protocols would use the default route, and ftp+smtp would use the route
directed by ipchains. Question is: how can I do that. 

I think IP alias would help. Basically, my need is to have a "privileged"
modem line that runs on a single Ethernet (bus via a gateway that has two
modems).

Thanks in advance,
Oki