SonicWALL VPN client through ISA Server

I have a client that has a network protected by a SonicWALL firewall. The issue I am facing is that they need to allow VPN access to people on a different network protected by an ISA Server.

I would really appreciate any help in configuring ISA server to allow the SonicWALL client (which we will load on individual machines) access to the remote network.