I installed one on my 05 636. Do yourself a favor and purchase the adapter. It makes life easier. I placed mine on top of the exhaust valve servo under the rider seat. The only thing I had to modify was the plastic on the underside of the seat for clearance. Love the alarm but my only bitch is that the battery doesnt last in the remote.
I used some extra lengths of wire to get into the fuse box at the front of the bike for the ignition kill. I tapped the line going to the ignition fuse. I highly recommend these: http://www.webbikeworld.com/Reviewed-motorcycle-products/posi-lock/ in the waterproof variety (find them at your local Kragen or Pep Boys). I used a fish tape to route the wires along the main harness back up under the tank into the under-seat area to the back of the bike.
I sat the perimeter sensor on top of my battery with the included velcro, and the ignition kill relay on the left side under the seat. I mounted the alarm unit under the seat. I cut out the tabs at the front and front sides of the underseat tray with a Dremel to give more room for the cables. I passed the cables underneath the bracket that mounts the rear seat / solo cowl. The perimeter sensor isn't as sensitive as I would like at the stock setting, but it can be changed. I haven't got around to it yet. Default if anyone gets right over the bike it starts to go off, but I'd like it to beep if people are in about 6 feet or so.
I don't know which remote you got but I have the TRS-6B which is the black rechargeable waterproof remote. I find it lasts about 4 days before it needs to charge, but the battery shows low LONG before it is dead (wait to charge it until it says pager off is what I do). It will work when it's charging so you can always plug it in and then disable the alarm if you need to. My bike's only alarmed at home, I work at a secure government facility so I don't worry about her there.