Don't Black Mamba's eat snakes? If so, just let one loose, wait a couple of days (be careful for it not to bite you in the face and kill you Kill Bill 2 style) and if your lucky, you should be able to find it about to eat your snake and get 2 snakes. If not, you keep the black mamba and still have one snake that you can use to get rid of people you don't like. You can't loose.

Unless it kills you.

Then you lose.

This can work, assuming you have a cool enough climate and screens on the windows to prevent escape.

Snakes like warm hot water bottles. I am not sure if they are still referred to as "hot water bottles" but its a rubber bladder that is used to place on swollen limbs and such.

Snakes prefer the dark so place it in a likely location thats low and dark.

Good luck.

I would try to avoid staking out a mouse as bait. Mothers tend to get cranky when they step on mice on cold dark nights.