Sure, you can run barcon cables under the bar tape and out near the stem for a cleaner look. You will definitely need longer than stock barcon cable housings to do this and also a longer than normal (as in tandem cable) rear derailleur cable. Rear derailleur cable length depends on your frame size. Regular road bike cable is just barely long enough if you want to route it this way. And make sure you run a nice arc for smooth shifting....
Here's how I routed the cables on the Moustache bar: