I wouldn't dye your vest, (if you are using the tacket twill that is) it won't take dye anyway!!! Best way to weather a vest, is with light application of greys/browns/blacks through an airbrush. Do some searching around, there used to be numerous threads on it..but they might be buried. Ive never done stove top myself, (except at Thanxgiving) LOL. Had pretty good luck just running things (like the coverall) through the wash to dye them.
D