Controlling wheelchair from computer

Hi,

I am embarking on a project where I wish to control an electric wheelchair via a software application.

The joystick on the chair is made up of 2 pots that provide variable voltage between 0 and 2.4vdc. When the chair is not moving both wipers measure

I am presuming that I could sumply get a dual digital pot that can be controlled from the serial port of a pc.

Could someone verify this and if so what parts can you suggest and whether they might be available in Australia.

Thanks