http://www.zoom.com/techsupport/adsl/adsl_5560.shtml
The above address is the manual of your modem. It made things a little clearer in my mind. First, the modem gives a IP to the router like 10.0.0.3 (you'll have to check the DHCP table to know the address used it is between 10.0.0.3-10.0.0.15). Once you found that IP, you'll have to enter it in the DMZ of the modem. That way all ports will be forwarded freely to your router. After that you just do the normal portforwarding config in the router as explained above (forward port 6346 to 192.168.1.102) and the forced ip in LW.
Bonne chance!