What needs to be done to convert a factory installation of a Sirius Radio module to an XM module? Can it be a simple programming service request through Sirius/XM?

If that is not possible has anyone just changed out the receiver module and used the same antenna, etc? What manufacturer and model of module should I get?

I understand the module is mounted behind the glove box. My biggest reason to switch is that I have XM in my Jetta, and there are a couple of programs and channels there that I really like that are not on the Sirius line up.