Firewall/NAT

hi there!
i am trying to use m0n0 as a kind of gateway between my LAN and a LAN-within-the-LAN.

let me explain:

i have set up a LAN 192.168.10.0/24, which is proteted by a content-scanning firewall. this firewall protects a maximum of 3 IPs. one IP is the firewall, another my workstation. the 3rd IP wpuld be the external interface of m0n0wall.

on the internal interface of m0n0wall the LAN-within-the-LAN ist set up to 10.0.0.0/24.

on the 192.168.10.0/24-LAN there is a static route to put all 10.0.0.0/24-traffic to the m0n0wall. how do i set up the m0n0wall, to put all incoming traffic 1:1 from m0n0-external to m0n0-internal, so that i can access any m0n0wall-internal adress automatically?

hasnt anybody got an idea, how to do this??