To answer your "where to go to get it programmed" question: You are not going to find any legitimate Motorola shop, or any radio shop for that matter to program a radio on a system it is not authorized on. IE if you dont have a legitimate radio ID on the system and permission from the state radio shop, no professional will do this for you. Ask if you want a good laugh. Also, the more you ask the "pros" to do stuff like that, the more "security minded" they may become ie "geez, we really need more encryption". Leave well enough alone, doing stupid stuff that could have consquences in the system at large does not help those that like to listen.
That XTS 5000 will not work in about a year or maybe up to 2 on the MSP system because it is going phase 2 digital.
The new system will be using P25 radio authentication so if you don't have a legitimate radio id on the system *AND* have it associated with your specific radio serial number, you could have a problem to include a bricked radio!
Yes you need a system key to edit any trunking parameters in motorola CPS. No, nobody who has it legitimately is likely to give it to you. Its possible to "make one" but not the best idea. You can do "non affiliate" scan if its set up properly but you still need to put in a radio ID that you could have made up and, worse, could belong to a legit user of the system. Then you do something wrong and it keys the emergency button for example, it could be a bad day.
Dont play with a system like that unless you are a legitimate user with the proper knowledge not to screw things up.