The technique I had out of the line was just step on the A key, balance the wiggle with the steering keys, if needed go from mashing A to tapping A and then you're off. Shame I don't have videos to demonstrate, but on keyboard you don't have many options aside from balancing the car steering like crazy. Wheels and GP3 never worked well for me, anyway. Tried once and never again.
Stats: 139 Starts / 7 Wins / 9 Poles / 5 Fastest laps