Rumba provides a ready-to-use workflow to export your Maya rig to Rumba.

Using the mtorba tools suite, you can first export your Maya rig and test it in Rumba, and then upgrade it using the specific Rumba features like the Rumba’s manipulators and the control of the rig by grips painted on the geometry.

You may start watching this video which will give you a good overview of mtorba: