I heard that JVM2 has a new feature that allows 2 tier commission structure for CB products. However payouts for the 2nd tier has to be done manually and through paypal. JVM2 merely tracks the data and statistics for you and your 2nd tier affiliates.
At the moment and meddling with it and using a hosted JVM2 solution with Ian at fireballcart.com , you might want to take a look at it.