I currently have mine mounted under the water bottle cage on the seat post. i have connected the right shifter to the left shifter. then a single long cable running form the left shifter to the junction B (4 way connector) in the BB. from there one wire goes out to the 3port junction box under the bottle cage. From there another cable goes to the front derailleur. There is a bit of cable slack that has to dealt with but no drilling of carbon is needed...and honestly, i never see any of it when i look at my bike plus i can still access while I'm riding if necessary. But its not perfectly neat and i know that bugs people.
Other options I've seen are the BLK-Tek bars http://www.blktec-cycles.com/collection ... roducts/r5
or the Syncros aero road bars that come on the 2016 Scott foil...http://www.syncros.com/syncros/global/e ... r-Stem-420
a friend of mine has Enve SES Areo road bars and PRO Tharsis stem. looks pretty cool. He daringly drilled a hole in the back part of the clamped section of the cars so the cables ran from inside the bars directly into the Tharsis stem. so the only. pretty neat set up...I'm too chicken to drill a hole in the bars until an engineer tells me it should be safe.
Dont know why more bars and stems aren't made to hide the junction box. it seems a pretty popular topic.