as a locksmith, you can buy a mortise lock installation jig.

cost is around 600$,
info:

Cuts a lock mortise in under 5 minutes! The new jig incorporates unique Quick Change Cutters, which allow the cutters to be changed in seconds, without removing the jig from the door. This means that both the full lock body and faceplate can be cut out with ease. The mortise hole is automatically centered on the door and accurate results are obtained every time. No other combination of tools can produce such fast and accurate mortise installations. The jig and its precision cutters will cut a mortise in hard wood, soft wood, composite doors and with the use of special cutters, aluminum doors as well, all in under five minutes! Contains carrying case, aluminum housing with hardware, 3 cutters, self-centering action, stops, long boring shaft (greater depth than any router) and instructions.