In CS6 its really easy. just camera track it, then make a null object (or a couple if you prefer) and then make a new 3d text layer (or you can make a couple of them and offset their position by 1 pixel each to make the illusion of it having depth, but thats a whole other thing) and then parent the position of it to the position of the null object that you created from the tracking data. To do this you can go into the position of the text layer, then alt click on the stopwatch/keyframe set button and it will bring up a little line to input code. You drag the little pick whipe (swirly icon) to the value that you want it to be linked to, in this case the position of the null object and then its going to link the two positions.You can also just right click on a tracking point and do create new text, but I find the null object works better since you can offset the position and have it floating, or use it as a referance for stuff.
To give it a shadow you can use the new ray tracer (though it takes years to render), or if its a relatively flat surface you can try just rotating a copy of the text so that it sits on the floor and then darken and blur it.
Once you have the 3d text you just have to mask out the skier, and anything else that goes in front of it using the roto brush or just manually with the pen tool. Then make this mask a new layer and put it on top of the text layer, so that it goes in front of it.
Theres probably a video on youtube about this also, which would be much easier to follow.
