Lock App to one of two Networkcards

To try and make a long and complicated description short:

At work i need to be connected to two different networks at once:
1. The local LAN i use to Print and Scan
2. A 3G modem i use to access a Internet database trough VPN to upload my scans.

When ever i am connect trough the 2nd network with VPN (cisco vpn client) and then connect the 1st network the VPN connection dies. This is because the VPN software switches from the 2nd network to the 1st that does not have internet access.

So the bottom line is:
Is there anyway to specifie what application uses what network interface?
There is no way to do this in the Cisco VPN App (that i have found), so this would probably have to be done on a system level?