You have to cut out the covering on the bottom of the fuselage and sand the clearance out for the cables. It's not as much work or as hard as it sounds. You can use a dremel with a snake attatchment, or you can use sandpaper wrapped around a pencil.

I'm telling you, pull-pull is a great system unless you're flying pattern.

p.s. Don't get those cables so tight that it's like a banjo. All you really have to do is just take out the slack.