I use FreeScan and thats how I have mine set up. I have the TMR 2 system set up as a system and I put every control channel and alt control channel for the entire province in as one SITE. That way as I travel the province, my scanner will continuously stop on the strongest control channel and as I move, it will lose signal and then grab the next strongest signal which "should" be the tower closest to me. This is the closest I can get to having seemless roaming like an actual TMR radio. However, like hfxChris said above, it will stop on the next freq it comes across which isnt always the one I want. I have to sometimes manually lock out a freq if I know its not the tower I want. It only takes a second to do that tho. Im OCD and thats how I like to have it set up, rather then setting each tower a new quick key.
If you have a scanner that you dont plan on taking out of your house, then all your should have to enter is the Control Channel and Alt control channel closest to you. If you dont plan on moving away from that tower, then you dont even need to program in the other two near you to be honest.