my suspicion is that you are not fully grasping how a trunked system truly works, which is completely understandable. I barely know how they work. but here are a couple things that you should need to know.
Mn/DOT doesn't have any frequencies that are designated to be used specifically for them when it comes to ARMER. The advantage of going to a trunking systems is that you have a common pool of frequencies that everyone can draw upon.
When you program your scanner, you just need to put in the control channel and the talkgroups you desire. Nothing else. The reason you don't need to program the voice channels in, is that the control channel essentially acts like an air traffic controller for planes.
For example, radio A wants to talk on talkgroup 123. When radio A presses their PTT button on a trunked system, Radio A is telling the control channel that I want to talk on Talkgroup 123. The control channel will then recognize that need and figure out what voice channel it has available to send this voice traffic to. once the control channel determines what voice channel is going to carry the traffic, it sends a message to all of the radios that are set to receive talkgroup 123 and says, "Hey, talkgroup 123 has some traffic that is going to occur on voice channel XYZ and you better be there or be square." If someone immediately responds to that voice traffic, they may again be on the same voice channel, but they may not. either way, the same process starts all over next time.