if by tuner, you mean the plug in contraption that alters the computer program, such as a Diablo, or Superchips, you cannot rent one, as the instrument can only be used by one vehicle. Using it on your truck, disables it, so it will not operate on any other vehicle.
The hand held programmer stores the original program from one truck - then puts it's program into that truck. It cannot be used for any other vehicle when it has the original program from another truck. I suppose they did it this way, so everyone would have to pay for the program, and not get a free ride.
I have a Diablo Predator hand held programmer for one of my trucks. I cannot use it on any other truck, without first removing the program from the first truck.. I can't use the thing, I can't let anyone else use it - it just stays there, in the truck, for if I want to change something. If I want to program my other trucks, I would need to either de program the Predator I already have, or buy another one; If I deprogram the one I have, the truck using it now, becomes stock once more. It is most annoying.