Limiting access to network on VPN connection

Hello, i've been trying to figure this out on my own, but
I need help so here it is. I have a W2k3 s/b server with
2 nics and PPTP VPN configured and working just fine. My
situation is that I would like to configure customer
connections and those customers would have only access to
one machine on the network, a machine that my local
network must also have access to. I tried to use the CMAK
and specify a route.txt file but I can't seem to get the
correct syntax to limit access to one computer. My
network is 192.168.123.0, the server supplying VPN is
192.168.123.202 and the only machine I would like the
customers to access is 192.168.123.210.

Regards,

Marc.