Yes, it's going to be tough, tough, tough. Bees in two sides of the house. The house is 150 years old, possibly an historic landmark perhaps? If not an historic landmark, it is surely highly valued for its age.
Man, I'm with you. I would want the bees too but whoever does this cutout will have to go thru either the outer brick wall or the sheet rock and inner brick wall to get to the bees.
Questions: Is it possible that the bees are "centrally" located with the hive and simply using two exits OR...do you have two separate, distinct hives.
You will need to locate the hive if you can before you proceed much further. I personally have an idea on how you might go about doing that so pm me if you would like to know. I'm afraid of being laughed at on the forum.
You will need specific permission since this is a residence with folks living there.
So many things to think about...
1. If you go in from the inside...can you put up a plastic sheet like a hazmat unit from ceiling to floor to keep the bees inside a very tight space rather than flying free around the room?
2. Perhaps a written statement of understanding that you don't pay for repairs and are responsible only for the removal of the bees, combs, etc.
I usually do my cutouts on old abandoned houses, etc. not current residences.
You have a fabulous opportunity in front of you. Best wishes and post up the results...with pics if you can get them.