Zeeaq,
the option already exists... you can select both mouse axes in the wheel-steering-menu.
Takes some time to get used to it, but is currently the best control method for laptop users (i.e. when no wheel is available).
Concering the proposal by himself, I doubt that using the mousewheel would word very well.. either it would be to insensitive or you would have to roll it constantly, which is also very uncomfortable... I suggest you try Mouse-y-Mouse-x instead...