How do I implement a custom message queue listener for WAS activation?

Question

I'm writing components of a .Net 4.0 web solution (on IIS7, WS2008), and need to provide a service which can consume messages from a message queue. I've found setup examples for configuring WAS service activation using MSMQ... but we aren't using MSMQ (using RabbitMQ) and I'm pretty sure I'll have to implement some kind of listener of my own.

I guess my problem is the system of configuration settings I'll have to set up is pretty opaque, and documentation is not clear.

so A: how do I implement and configure a custom listener for WAS service activation.

and B: any advice for configuring the rest of this setup would be wonderful.

Thanks