Alright!
HID's work fantastic on the Tenere thanks to the projector lenses and the mechanical high beam shutter.
If you want to go with the simple route, get 35 watt HID's, and you can plug them right into the factory headlight bulb plug. Drill the holes in the back of the bulb covers, and either zip tie the ballasts to each side of the fairing near the forks, or jam them up behind the windshield (and plastic cover) and you're done. 35 Watt HID's are a vast improvement over the factory headlights (which aren't bad to begin with), and they'll go from the OEM yellowish light, to the HID white or blue.
A more complex install involves adding a relay to the system, but this allows you to safely go with the 55 watt HID's, which are a substantial improvement over the 35 watt HIDs, and a night and day difference over the oem halogen. Same idea with the physical install, but there's a little more to wiring in a relay:
Terminal 30 goes to the battery, with a 10 or 15 amp fuse in line.
Terminal 85 goes to a ground.
Terminal 86 goes to the factory headlight positive wire.
Terminal 87 goes to the 2 red wires coming from the HID Ballasts.
Ground the 2 black wires coming from the HID Ballasts.
I mounted my ballasts inside the fairing near where the winglets mount. They are hidden when sitting on the bike, or looking at it from either side. There is one ballast on each side.
Some final information:
The factory low beam cutoff is unchanged with these bulbs, so those complaining about not being able to see through turns (because the cutoff isn't allow light to shine 'up' when leaned over) won't be satisfied.
4500k color temperature is clear white. The higher the color temperature, the more paint is applied to the bulb, so the more blue it will look, and the less lumen output they will provide. 4500k is the whitest and brightest.
Whether you're running 35w directly off the factory plug, or 55w through a relay, power is always available at the factory plugs, so you can always put a regular H7 bulb back in.