What I've done.

Put rit dye into the washer, then set to regular wash (and I have had no problems with hot). Add UK after washer is filled. Sit there with a book, and every time the washer starts to drain, set it back to agitate. Repeat as necessary (probably 3-4 times depending on how dark you want - over an hour if you want really dark). Once you think it has been in long enough, go ahead and let it drain. Add about 1/2 bottle vinegar to the rinse. Then wash 2 more times (go ahead and use cold this time) with soap powder to make sure the loose dye is gone (adding fabric softener also fun at this point, it really helps with the wear of a Workman's). Hang to dry (it is the dryer that shrinks stuff not washing in hot).

Note, unless they have changed thread, the kilt will dye, but the threads wont. Gives you kind of a levi's look.

Adam