I used cc1101 EVM (http://www.ti.com/graphics/tool/CC1101EMK868-915.jpg)
Well the driver is a very simple SPI driver and I'm sorry I can't share the driver as it is a part of a current cooperate product. First thing is to create a simple SPI driver and test the proper communication between the gumstix and the cc1101. Then you can start the rest of the work.
You can start with this (http://www.jumpnowtek.com/index.php?option=com_content&view=article&id=57&Itemid=62)