[LARTC] 2 internet connections for 2 different purposes

[brooke]

I've got a linux machine (fedora core 3) with 4 network cards.

I looked at the howto and the only example that is close to what I need 
to do is section 4.2 on multiple uplink providers. I feel like I'm so 
close but just can't get my head around the final part.

Here is what I have

eth2 and eth4 connect to 2 different isps.
I want all connections the come from my dmz on eth3 to go out of my 
connection on eth4
I want all connections from my local network on eth0 to go out of my 
connection on eth2

can anyone help me out with this?
thanks in advance
Brooke