I have done it many times. You need to be sure that the wallpaper seams are flat and that the wallpaper is in excellent shape. Then I sponge the first color on. This gives me control of the moisture applied to the paper and will prevent buckling because of water seeping thru the paper.
After that coat is dry, I glaze the second coat and it is a beautiful effect. This actually prepares your wall for actual painting later on if needed. The key is to minimize the moisture on the wall. However, I do usually sponge and then glaze the wall and the end result is professional. good luck.