A Live surface has been around since pre-Maya 6, I am pretty sure. It is the plain Magnet icon next to the rest of your snaps on the top right. I import two instances of the "medium poly" (a lower subdivision level of the high-poly version) and put them on the same layer, I make one semi-transparent with a Lambert…
Just freeze the high res mesh and make it semi transparent, and then build up the low res mesh like you normally would using the high poly as a guideline to base it all on. You could might be able to find a script to snap it all together, but I doubt it would even save you that much time. You still have to build the whole…