I added an eLite Jr. Signature MCU and a couple LED cables from www.lifelites.com to a LEGO 8201 Classic Mater. Now he lights up!
I removed the original power switch and added a larger one which protruded down far enough to access without effort.
I also removed two of the LED sockets and hard wired two LED cables (custom length of about 2.5 inch each) to the MCU. There's enough slack wire to remove the MCU for battery changing.
Modifications on some of the LEGO pieces included hollowing out one of the 2x4 bricks to house the eLite Jr. MCU, as well, as drilling holes and grooves to run cables through. I also drilled a hole behind the head light on the front fender for the LED and drilled a hole in the back of the same fender to run the wire through to the MCU area. No modifications were needed for the roll bar light area after drilling a hole through the model to get a cable through to the upper part.