I would have to chime in and agree with the wizard. I've made two kilts and working on my third. The first and last are traditional kilts as described in The Art of Kiltmaking.

The second followed those same instructions except that I included pockets. Aside from having to allow enough extra material to account for those pockets, I had to modify the inner construction to work around the pockets once they were there. The manner in which the wizard constructs pockets retains strength and durability despite a large opening in the fell stitching, in part how the pocket is integral to the construction. His method of inner construction is also uniquely suited to the addition of things like pockets.

If you were somehow to work around the inner construction, and somehow successfully insert a pocket, I suspect that you would likely encounter failure of the fabric at the top/bottom of the pockets after any amount of use.

If you still wish to go ahead with such an experiment, I wish you good luck, but would rather recommend making or having made a contemporary style kilt if you truly are set on pockets!

-J