Get yourself one of those concrete A/C mounting pads. Set your pump on it and mark for the mounting holes. Drill part way through the pad with a masonary bit a few sizes larger than the threaded rod you plan on using. Install some short pieces of threaded rod using some of the high-tech adhesives available for this purpose. Once the adhesive dries/cures, put the pad where you want it and bolt the pump down. Once you close and lock the door - theives will be hard-pressed to walk off with your pump.

Later . . .

Jim

[Linked Image from cruisin66.com]