As far as the high beam and neutral indicator go, you can always get two LEDs from radio shack and just use a clip that clips onto the line for those indicators and into your new line. I would definitely use a 12v test light and only do this if you're feeling froggy.
But once you get those installed, you're only other big step will be mounting it and making it look good. But as long as you keep your gauge cluster, you could always re install it before selling it, the mileage wouldn't be accurate, but as long as you can wade into those legally murky waters it'll work. I think there are places on most titles that will allow you to state the mileage isn't accurate.
Few problems on this green earth cannot be solved by the proper application of high explosives
'96 Vulcan 500LTD
'08 Vulcan 500LTD (wife's)