[gpetilli]

I don't know if this is a live thread, but I will suggest two options anyway.

If you want to use the WPI code you linked, the most straight forward method would be to use CAN Jaguar speed controllers and hook up encoders on each wheel connected directly to the Jaguar. Then you setup the Jaguars to do the PID loop on each wheel. There are many posts on how to do this, but the most successful seems to be to adjust the I term first and then the P term.

The other option would be to write your own Holonomic code - it is not that difficult. Ether has a link to some pseudo code that works well. My team took this approach and the robot was driving in about an hour.

To address the wheel speed issue, the consensus is that you need gyro feedback. Keep in mind that even if the wheels are all spinning at exactly the correct speeds, the force vector they create is a function of the weight on the wheel. If the CG is off or one wheel is lifted off the ground the robot could spin violently. The gyro can help redirect power to the wheels to compensate.