Force use of outgoing IP address

["Neil Russell" <NeilR@mulberry.com>]

Hi,
 
new to all this so please be gentle with me....
 
I have a linux router with 3 network cards in, each card has multiple IP
address's assigned. I want to route all aoutbound traffic TO a
destination port of $DESTPRT out of eth0 on its IPAddress of 10.0.0.2
 
 
Example is 
 
Eth0 has IP address's of 
10.0.0.1
10.0.0.2
10.0.0.3
and connects to 10.0.0.99 (Internet router)
 
eth1 has ip address's of
192.168.0.1
192.168.0.2
192.168.0.3
 
 
and eth3 has ip address's of
192.168.1.0
192.168.1.2
192.168.1.3
 
 
So ALL traffic on the router with a destination address MUST go out on
eth0 and show its IP address as 10.0.0.2 even though the default route
is out via 10.0.0.1
 
Hope thats clear and that someone can advise.
 
 
Neil.