each single led uses one port on a lighting controller. something like the ledwiz has 32 ports and the pac led64 has 64 ports.
If you were using RGB leds, then each rgb would use 3 ports (one for red, one for green and one for blue)
so if you're only lighting the 22 buttons on your cp with single color leds, then thats 22 led ports.
Don't forget, if you plan on using regular leds, you will need resistors in series.
both Ultimarc and Groovy Game Gear have full documentation on their websites