Gilmore,

There really is no one particular way to do this, so I doubt you'll find directions anywhere.

Usually when someone wants to sew the pleats in a belted plaid, they are wanting to preserve the look of a randomly hand-gathered garment, only make it easier for them to put on. So there is no need to make the pleats regular and even. In fact, making them irregular will add to the authenticity of the look.

I'd just pleat it as you want it to look and pin those pleats in place. Then, the quick and dirty way would just be to sew in line of stitching in across the pleats at the waist, and let that be that. You can potentially do this on a machine.

When I sew the pleats into a great kilt for a client, I will actually sew each pleat down by hand, just like I do on a modern kilt, only for 2" at the waist. I think this will give the pleats a bit more strenth than a single line of machine stitching will. And the 2" of stitching is completely hidden by the belt.

Additionally, I usually add a couple of belt loops (unless the client doesn't want them), to facilitate putting the whole thing on.

Again, I do the pleats at random, and slightly irregular sizes, unless the client is specifically wanting a more neat look, in which case I pleat it to stripe, with regular size pleats.

M