I need help with this also. We have a cable internet connection (16Mb/s) and a T1 (~1Kb/s). This is causing a couple issues with bandwidth sharing. One of our people is using a VPN and having issues when I plug in both networks as I think most data is going over the cable connection, and a small fraction is attempting to go over the T1, and thus ruining the VPN and stopping the VPN connection.
How can I set up the router for load balancing, but to force some connections over the cable connection (unless the cable is down and thus use the T1).