I found a great source for modifying a jacket by Alan H:
http://www.geocities.com/alanhsails/...t_jacket3.html

This is the explaination for why you want a patch pocket:

You want patch pockets on the outside of the jacket rather than slash pockets because the pockets in a kilt jacket are in a different place than they are in a sportcoat. They're higher up and further back. Patch pockets can carefully be cut off and the material used for ersatz pocket flaps, slash linings even epaulettes if you have the energy.