In the following files you can find code for AVR micro controllers to use this modules.

Source (.c) file: hopeTx

Source (.c) file: hopeRx

PDF file: RFM12B

RFM12B and AVR - quick start
I found this tutorial when I searched for connecting this module to AVR.
You can download the tutorial at: PDF file: zenburn.net

My Experience
My attempts to get this module working were all unsuccessful.