best way to do it, done it on a few Transition frames is feed some gear cable through the hole at bottom bracket from the outside into the seat tube, when the cable comes out the top of the seat tube use the red double ended connector to attach one end to dropper post at trigger end ( unscrew the cable at trigger end, its a threaded barb) then just carefully push & feed the dropper post cable through the bottom bracket hole. Simples..
cable tie along frame & cut to required length & re screw onto barb on the trigger device