ouch man....thats gona be impossible to make for a beginner, and hard for someone experienced too. but if you want to give it a try i offer you my help.
i sujest making a track with straight sections only, and at each "intersection" of the sections, you have a "checkpoint" to switch the gravity checking method to the next angle of the track... before doing this, try searching on google for free 3d models or something like that to find a good mountain, and once youve got your mountain, "build" your track on it so its flat in sections as before... madden made a skiing game once i think, try finding it on the forrums, it might give you a refernece to start with...
rick