uv pass from maya mental ray

create an render layer call uvPass_R

add a new Custom Color pass in render setting and rename call uv

and send the uv pass to uvPass_R render layer

need mib_texture_vector / surfaceShader / writeToColorBuffer

connect surfaceShader to writeToColorBuffer

connect mib_texture_vector to writeToColorBuffer

in writeToColorBuffer > Frame Buffer Options > Customer Color Pass set to uv pass

in mib_texture_vector > Parameters > project set uv mode

last step assign surfaceShader to objects and the final node graph will be like this