The Maya api samples include an example of how to connect external devices. You can find an example in the maya application directory in `devkit/mocap', which includes a C++ project that uses the maya Mocap api to output continuous rotation values based on the system clock. I've seen this used to add support for joysticks and game controllers:
http://download.autodesk.com/global/docs/maya2014/en_us/index.html?url=files/Motion_Capture_Animation_Server_.htm,topicNumber=d30e260341
You'd want to replace the clock part, of course, with something that spits out controller values you care about.
The maya side is handled by scripts that connect incoming "mocap" data to different scene elements. There used to be generic UI for it but nowadays you have to do it all in script:
http://download.autodesk.com/global/docs/maya2014/en_us/index.html?url=files/Motion_Capture_Animation_Server_.htm,topicNumber=d30e260341
I'm not too up on the current state of the art but some googling should show you how to attach device inputs to the scene