You will likely not find an exact clone of ShockTop here. However, I would recommend taking a look at the Recipe database here. Look in the Belgian Ale section and you shoud be able to find a belgian wit recipe. You could also look at some of the American wheat recipes also as those are pretty similar and you could substitute a nice Belgian yeast. ShockTop is not likely to exhibit enough of a true Belgian character that the difference between an american and belgian wheat would be too far off.