Help with controlling 3 dc motors with arduino uno and adafruit motor shield

I am new to the arduino experience, and of course my first project is a hard one. Some friends and I are building a life size R2-D2. We want to keep it simple. 3 DC motors; 2 to control movement and turning and one for the dome rotation. All of this of course controlled by a 2.4 Ghz RC control.

I have a 5 channel RC receiver, the Arduino uno and the Adafruit motor shield. I have been looking all over the place to get some insight into getting the rc ppm from each channel and turning it into commands for the motors speed and direction. Do I use PulseIn()? has anyone out there done this?

There is probably a post some where about this but can't find it.

I am using a Gel lead acid battery to power the motors and a LIPO battery to power the electronics.

HELP!