Ok - don't laugh....when I put sprinkles on the side of a cake, my floor is a disaster afterwards...BUT, I kind of throw them on in small spurts...you can also gently pat them on from the palm of your hand...Just be prepared to clean up the counter and the floor when you're done!
I had a heck of a time with my tire cake - choc icing COVERED in black jimmies...good thing I love the kid I made it for! haha!
Also - if you are using BC, I'd put them on before it crusts. They won't really stick otherwise. Good luck!