The Excelleron has all the guide tubes for the steel cables already installed. Very detailed instructions on how to make it work. Essentially, each elevator half is hooked up just like a normal rudder pull/pull setup works. Each elevator half has a top and bottom cable that goes to the same hole on the servo arm. Just like a rudder, setup with relatively-matched tension on the cables, with control takeoffs the same distance from hinge line.

Pic attached of what the servo end looks like (although not an Excelleron, it's the same idea.