[Alan Anderson]

LabVIEW makes it easy.

In Begin.vi there is an Open 2 Motor Drive block. Delete the PWM and Inverted constants connected to it. Right-click the block and replace it with an Open 4 Motor Drive. Create constants on all of its inputs and assign the correct PWM outputs to the four motors on the corners of your drivebase.

In Teleop.vi there is an Arcade Drive block. Replace it with a Mecanum Drive block and figure out what joystick axis you want to use for rotation control.

That'll get you started. If you have specific questions, we can probably give you helpful answers.