If I had a sample cake to practice with along with jimmies/crumbs, I’d try this experiment (no clue if my thinking is way off wack). Brush shortening on a piece of wax paper, the length of the cake’s circumference, sprinke on jimmies/crumbs and gently press down. Next lift the wax paper up next to the cake (jimmies/crumb side against the cake), HOPE the jimmies/crumbs stay on, and gently press the back of the wax paper against the cake, all the way around. Refrigerate an hour then slowly peel the wax paper off, HOPEFULLY leaving an even coating of jimmies/crumbs stuck to the side of the cake.??? No clue if this experiment would be too far fetched/wishful thinking.