How do I convert Maya models to the Source engine format (.mdl)?

I have a bit of experience using Maya to create 3D models. I understand I need to keep the models below 10,000 polygons.
How do I go about converting Maya models to the .mdl files that the Source engine seems to use. Do I need to convert the .ma to obj? What software do I need for the conversion? Do I need to create a physics model to add to the file?
I’m planning on making some models for SFM.