[ozrien]

Got this working on my bot. I used 3,1,4,5 for LeftFront, LeftRear, RightFront, RightRear respectively. Also added gyro an analog0 so holds absolute angle.
-I use the F350-similar gamepad (the wireless version), so I changed the three axes to X,Y,Z.
-Also I added button5 so that it will reset angle, thus allowing you to reselect the angle heading to servo to.
-Also inverted my right side since right-side motors have to drive negative (red) to move robot forward.

Actually I've been playing with this for about half an hour, driving it around the CTR office, so it seems pretty good.

#include "WPILib.h"
class MecanumDefaultCode : public IterativeRobot
{
	CANTalon lf; /*left front */
	CANTalon lr;/*left rear */
	CANTalon rf; /*right front */
	CANTalon rr; /*right rear */
public:
	RobotDrive *m_robotDrive;		// RobotDrive object using PWM 1-4 for drive motors
	Joystick *m_driveStick;			// Joystick object on USB port 1 (mecanum drive)public:
	Gyro gyro;
	/**
	 * Constructor for this "MecanumDefaultCode" Class.
	 */
	MecanumDefaultCode(void) : lf(3), lr(1), rf(4), rr(5), gyro(0)
	{
		/* Set every Talon to reset the motor safety timeout. */
		lf.Set(0);
		lr.Set(0);
		rf.Set(0);
		rr.Set(0);
		// Create a RobotDrive object using PWMS 1, 2, 3, and 4
		m_robotDrive = new RobotDrive(lf, lr, rf, rr);
		m_robotDrive->SetExpiration(0.5);
		m_robotDrive->SetSafetyEnabled(false);
		// Define joystick being used at USB port #0 on the Drivers Station
		m_driveStick = new Joystick(0);
	}
	void TeleopInit()
	{
		gyro.Reset();
	}
	/** @return 10% deadband */
	double Db(double axisVal)
	{
		if(axisVal < -0.10)
			return axisVal;
		if(axisVal > +0.10)
			return axisVal;
		return 0;
	}
	/**
	 * Gets called once for each new packet from the DS.
	 */
	void TeleopPeriodic(void)
	{
		float angle = gyro.GetAngle();
		//std::cout << "Angle : " << angle << std::endl;
		m_robotDrive->MecanumDrive_Cartesian(	Db(m_driveStick->GetX()),
												Db(m_driveStick->GetY()),
												Db(m_driveStick->GetZ()),
												angle);
		/* my right side motors need to drive negative to move robot forward */
		m_robotDrive->SetInvertedMotor(RobotDrive::kFrontRightMotor,true);
		m_robotDrive->SetInvertedMotor(RobotDrive::kRearRightMotor,true);
		/* on button 5, reset gyro angle to zero */
		if(m_driveStick->GetRawButton(5))
			gyro.Reset();
	}
};
START_ROBOT_CLASS(MecanumDefaultCode);