Because the wireless module needs 3 volts, we will need to modify the teensy to run at 3 volts by cutting some traces and adding a voltage regulator. Instructions for this are on the teensy website.

Attach the other nrf24l01 wireless module to the teensy.

Put the teensy in some sort of enclosure. I used a pill bottle. 

To make the wire go through the cap, I drilled a hole just big enough for the wire, then cut a slit in the side to slide the wire in.

Now just record your macros. I wrote a program for this, but you dont need to use it.

click a switch, click record, type your keys, hit record again when done.

once all your keys are set how you like em, click the generate code button and the code for the teensy will be copied to your clipboard.

paste the code into the arduino ide, select the teensy board, set it for 8MHz clock, and program it.

enjoy your keypad.