I have two MX7000 lightbars that I bought locally. Both were pulled from police cars and the wire harness was simply cut off. If I understand your question correctly, you want to know which wire goes to which component on the ightbar; e.g. this wire goes to the rotators, this one to the intersections, alleys, takedowns, etc.
The simplest way to figure that out is to tap the wires to your car's battery. By doing this you'll learn that the blue wire leads to X, the orange to Y and so on. Not only will you discover which wire does what, you'll discover what components are working or not. I gleaned that from the aforementioned "useless" installation manual.
As far as wiring it to controls, that manual that Boomer posted is indeed no help at all. It shows you how to hook the built-in Arrowstik to a control head, but leaves the rest of the bar for the operator to deal with.
You can wire up custom switches like Foom Man did, but for the love of Pete, use relays between the battery and the switch so you reduce the risk of the switches melting.
Personally when I get around to wiring up my light bars I plan to use something based on a discussion I had with Bryan a few weeks ago:
It's a Federal Signal Unitrol Omega 9000 control head and you can pretty much wire up anything in your light bar to any switch on there. With all that's going on in an MX7000, multiple switches are needed.
Somehow there's always someone who can do things thought impossible, simply because they do not realize that they should be incapable of the achievement.