Hi Scott,
I worked with sip-puff for Morse code decode years ago. You must have something similar to use the web.
I think many modern sip-puff units use small pressure sensors with a analog output. Maybe you could run one of these to an Arduino analog inputs and then have a variety of responses. Maybe puff pressure controls speed?
Do you have any other eyebrow/blink sensors? Maybe you could end up with direction and speed and really run a car all over..
Let me know if you want an Arduino starter kit to play with; I'll send you one if you'll document online what worked for you. I'd like other people with similar limitations to see this stuff...
PM or email terry@yourduino.com