valentine one rader install

Hey all glad to be a part of the group but i already need help from you. I do a lot of traveling so I bought a valentine one radar detector so i can travel faster. I have a 97 Olds Cutlass Supreme. I want to hardwire the radar so there are no ugly wires hangin down. I need some advice on where to wire the radar to. I have map lights built into my rear view mirror. I think I could tap into those wires as long as I have a hot and a ground. What do you think. Could i do this. I havent recieved the radar yet so I dont know what the kit looks like. It comes with a hardwire kit though. If I could do this could I just soder in the ground to the ground wire or do I have to find a separate ground point for it. If I couldnt wire the radar here any suggestions would be awsome!!

Thanx in advance!!