There is some kind of sweet spot you need to hit - days/times when they have extra staff, but not when the ride is extremely busy.
We did the tour at the Twister ride and it was cool. They took you up to the control booth and explained a lot about the show, building, and effects. Then we watched the show from the control booth and when the show was over, we watched all the effects reset.
We've tried maybe a half dozen times at each MIB and Mummy and haven't hit it at the right time. Once, for Mummy, the TM at the front said she couldn't give the tour and said she would see if she could find someone. We followed her through some TM areas and took an elevator up to the load platform. She had us wait there and she went to look for someone. After about 5 minutes, she came back and said they were too busy to have someone give the tour, but she'd get us on the ride.
She walked us to the loader and we got on the next car.