Order these:
http://www.warmnsafe.com/index.php?main_page=product_info&cPath=65_71_83&products_id=219
Also order two set of the new grips of your choice.
And order some of this. Available at Home Depot or from many sellers at Amazon:
http://www.amazon.com/Rescue-Fusing-Silicone-Repair-Black/dp/B001JT0EL6
Take the stock grips off. On the clutch side, wrap the bar in a couple layers of rescue tape, until it's about the same size as the throttle side with its plastic tube. Then put the heater on, then put a throttle side grip on. The reason for this, is because the metal bar is a big heat sink and if you just put the heater on bare metal the clutch side won't heat as well as the throttle side.
Install the heater on the throttle tube, and install the grips over the top using your preferred method to glue them down. (Grip glue, hairspray, rubbing alcohol, whatever.
Install the dial somewhere elegant. Run your wiring nice and clean.
It'll look cleaner than factory, you get to have whatever grips you like, you'll get the most possible heat for the number of watts you spend, the most fine adjustment, and it's realtively inexpensive. Slightly more work, and you do have to drill holes, but I think it is worth the trouble.