Tyler Good posts a method for quickly bake a normal/AO map with xNormal without ever leaving Maya with his Bake Layer Tool for Maya.
Tyler Good warns that “This tool/plugin is still in beta, and at the moment, I am still trying to acquire node IDs from Autodesk. Because of this, maya files using the bake layer nodes will break upon upgrading to a version of this tool 1.0+. I will attempt to write a tool to fix broken .ma files (.mb, you’re on your own) once this happens, but I cannot guarantee it will happen.”