grad prank, brake to horn

So we're pulling a grad prank on a friend, and it is the classic brake to horn prank :) I have some knowledge about electronics, but not sure how to approach this one. So it's a 2005 Dodge Dakota, and I've got some wiring diagrams from here . So if I use a relay, have the brake wire, WHITE/ lt. blue, go into 86, 30 to battery positive, 85 to ground and 87 to horn trigger (-) dk. GREEN/ purple, would that work? or is there an easier/quciker way of doing this? Thanks!

12V+ output from brake switch to 85, ground to 86 and 30, 87 will provide a negative output to the horn switch wire. the12volt • Support the12volt.com

Sweet, thanks for the fast reply. Another quick question, don't know if you'll have an answer but, is there another place aside from the cluster harness I can get the Horn (-) Trigger from like the ignition harness or somewhere that doesn't involve ripping apart half the truck ;) Thanks!

Horn switch wire should come down the steering column. According to bulldog website: HORN      DARK GREEN/ PURPLE (-)      @ HORN SWITCH