3 motor vehicle - help

Hi. I would like to use RobotC Graphical to program my robot to be driven by the controller, but I am having some difficulty with the options.

I have two motors on the rear of the vehicle, connected to port 1 and 6 in a standard configuration.

Port 10 I have connected a third motor that is controlling the steering arms that can swivel each front wheel right and left (similar to an actual vehicle)

The problem is that with only tankControl or arcadeControl I don’t know how I can simply program it to drive.

I want the left joystick forward and backward to link the back two motors together for forwards and backwards, and the left and right joystick movements to turn motor 10 (or failing that, the right joystick to turn motor 10)

Any ideas, or can it only be done in proper robotC non graphicaR