Dennis Kirk sells little heat cartridges that go inside the bars. There made to fit steel bars, but you can ream out the end of alum. bars and make them work also (no bark busters) $13 bucks makes a cold day a lot nicer.
i used the i used the grid type warmers that wrap around the bars last year and they worked pretty wel.this style allows you to run bark busters on your bike too.i think they were about 25 bucks.
i got them from dennis kirk i think enduro engineering also sells them.i run the msr mud/windguards on my barkbusters too.you might want to wrap your levers in some type of cloth tape too,it seems to keep your fingers a little warmer in you ride with your fingers on the levers. what kind of tires are you running? studded?
You need to have a lighting coil to run these. I use them on a KDX but it don't put out enough juice to run both lights and heaters at the same time. On my wife's 300EX quad with a battery it runs both fine.
The wrap around version is very nice - they cost me $25 through my local dealer. The flexibility of running bark busters is a must have if you run in the trees!