X, Y touchpad with capacitive sensor

Hey guys. I have ordered the MPR121 on a breakout board from sparkfun. It is a I2c capsensing chip with 12 capsensing pins. I am working on a project which will need to use a touch pad to work. Basically I will be printing out this color circle: http://imgur.com/uu9eep4 it will have a radius of 2 inches.

I am hoping to have it control rgb leds (obviously whatever color your finger is on, the rgb leds change to) but i have one problem... I have absolutely zero idea where to start or what to do now!

I have made touch sensors before, even scroll wheels that use 3 touch sense pins... but I have no idea how i would design a touch pad, and what the sensors will look like (i.e. shapes) and what the code would be like.

I know i have 12 touch sensors at my disposal, but I need many of those other ones for other buttons, so i need to use as few of those pins as possible.

Please let me know if you have any advise on how even start this project!

I would really appreciate it