Seting up WINS replication thru firewall

Does anyone have any detailed advice on setting up WINS replication thru 2 firewalls that are using NAT (both Netgear RO318s)?

I have two networks (Both Seperate Win2K Forests) connected via demand dial PPTP. Manual 2 Way Trusts have already beenset. Connections work great and can call up computers across VPN manually but no browsing. Can’t get WINS replication to work…

Thanks