Positive goes to a switched power supply so that's it's only on with the bike, negative can go to the battery.
As far as installation, the beauty of this is you can install it anywhere you want on your bike. I was going to epoxy the led into a short piece of stainless steel tubing and mount it down by the oil pressure sensor so all I would do is look down to see what color the led was. It's up to your imagination.