Remote connectivity for specific IP requests

Hello to you all!

I have a VPN connection to a remote network. On that remote network i have a windows XP computer from which i would like to route back to my VPN client, but only for a specific IP request (since the required ports on the remote network are closed). How could i achieve that? Please note that I can succesfully ping my VPN client and use remote desktop from the remote network XP machine..


VPN client (10.111.1.21)
Win XP on remote network (10.110.17.75)
IP for which i would like to enable port forwarding is 212.16.18.37

that way i would be able to bypass the "default gateway" for requests to 212.16.18.37, send them to my VPN client and process them there with the open internet connection (with the required ports open).

I guess i will have to work with "route add", tried that already and got the packets onto my VPN client, but the client hasn't forwarded them to the original destination (per internet) nor did he return the result to my remote XP machine...

thanks very much in advance!