What excactly do you want to do?
Does it have to be hotlap-mode or just "one car on track"?
If the second, maybe you could run local server so track&error is already set and join via join-URL.
Then you are spectator, join via ctrl+j or something...
I'm going to throw this out there and it may not even be possible to do. I was having trouble getting my wheel that I made out of a optical mouse to work on my arcade because it was reading a little y movement along with the x movement and was confusing it. I used X-Mouse Button Control and made it to where I could hold down a hot key and only get x movement long enough to set my controller. If you could get your wheel to act as a mouse with vjoy or something like that you could have x axis at all times and have it change to y axis while holding a button on your wheel. You would be able to move your mouse to any position on your screen with your wheel but it would be like using one of those claw toy machines. Just and idea.
Cheers, Gutholz is as close as i can get at the moment and it's what i'm currently doing with 2 buttons /ready and /join, I just wondered if there was a way to land straight on the track in the car from the desktop.