I just installed mine last week on a 2014 SGS......I used the factory Aileron heated grips.
I agree the directions were freaking awful here so let me see if I can add some tips based on what I learned doing the install;
There are 2 basic circuits, 1 is the circuit that runs between the 2 grips and the second is the power circuit.
The circuit between the grips is pretty easy.....you simply run the wire from the left grip (the one inside at the end of the grip through the bars. The wire from the throttle grip is already wired and part of the throttle wire assembly. you will need to remove the little black cap at the end of the electronic throttle assembly, remove the cover at the end of the grip. You will plug the little wires there into the end of the throttle assembly (need needle nose pliers here) after you slide on the grip, line it up on the throttle assembly in the position you like and then pop the end of the grip back on.
You will need to eventually connect these 2 wires from the grips together and this is done by stripping back the wire in the throttle loom, and replacing the plug there as outlined on page 3, #3 in the supplied directions. You basically need to crimp on the 2 supplied pins, after removing the factory connector which will allow the cable from the left grip to be connected.
Then you will need to modify the left hand grip by notching out a piece of the grip in the channel near the end that goes into the switch housing, then feed it through the switch assembly and out the other side where the wiring harness exits. If your bars are drilled you can run the power wire through the bars (There is room) or run the power wire along with the external wiring by bundling with the switch housing wire and re-attach to the bars with the supplied wire ties.
Once you have all that you'll need to remove the gas tank and either relocate it to the seating position (with shop towels or a cover) and remove the plastic center channel where all the existing wires are currently run and run it to the back of the bike as you will eventually be connecting it under the left rear cover.
Now you will need to install the Electrical Connection Kit, Tour (69200722) which will supply both the switched power, hot lead and ground and as a benefit you will also get an accessory plug for future things like a heated seat as was standard on models through 2013. (this is a $25 part). Make the proper connections, button it up and they should work...............it was a bunch of work.
In hindsight it is one of the few times that the one hour labor quote from the dealer would have been an EXCEPTIONAL deal.......if you haven't installed them yet I suggest that you call your dealer and ask they fee to install........after the fact $100 would have been a good deal for me to have them do it.
I am very happy to have them however and they were VERY welcome on the 300 mile ride home Sunday with 40 degree temps
