I had the BT45-HON3 installed a while back (early 2015 I think). Works great. It seems easy enough to install yourself, the most difficult part, it seems to me, being running the microphone to a good spot everything else happens behind the back seat. The only reason I had it installed was due to having an unheated garage and getting the thing in the winter! I actually wound up moving the unit and the mic anyway.
As I recall the instructions, in a nutshell, you pull the back seat (this can be a trick depending on how daring you are. Search here and you'll find instructions.
This one is good.), unplug the XM/Sirius cable from the receiver, located on the passenger side, back wall, plug in the cable that comes with the BT45, plug the XM cable in to that, plug in the mic and run the mike to where you like it. Put it all back together.
Do a search for for the BT45-HON3 here and you'll find a few threads on it.
This link looks good and includes a look behind the rear seat at the tuner and a link to the manual (USA Spec has the manual online too). The manual doesn't go into detail on how to run the cable if that is what you are looking for. I can imagine that "awesome" instructions might include that but I don't know what else it might include. The install seems pretty straight forward.
In my case, the Bt45 unit ended up behind the finish trim under the back seat velcro-ed to the carpet. I wanted to keep it reasonably accessible in case I wanted to utilize the USB port. My mic is stuck on the roof console on the drivers side (where the sun glass holder/home link buttons are). The mic cable runs up rear driver side, to the roof under the trim then to the front.
Alternatively, an add on XM tuner could be mounted under one of the seats I think? Drivers side maybe? Dunno for sure. Mine was with the truck and is behind the back seat as described.