I finally added mine - Here is a copy of what I put on another thread in case anyone finds this and wants to install it for themselves -
I finally got around to installing a brake lamp on my 01 Rancher 350 FE ES.
Here are some pics. The most important part was the brake lever switch which is (Part # 35340-HR0-305) I installed the lamp on the rear flip down storage door. You'll also need a screw to mount the switch. (Part # 93893-04020-07) The screw will be a little long, but cut it back with a hack saw if you need to. This switch mounts on the bottom of the hydraulic lever, or the top of the non hydraulic lever. If you mount it on the non hydraulic lever, youll need another part. It's a square block looking washer that places the switch at the right height. Honda calls it a collar. ( Part # 35345-HF1-830)
I didn't use a relay. Just an inline fuse holder and the switch with some 18ga wire. No need for a relay on such a low current application in my opinion. It's wired as switched hot.
Hope this helps someone.