I worked at installing the cross levers on my cyclocross project bike. I removed the handlebar tape back to the aero brake levers. I removed the cable from the housings. Next, I cut the housings to fit between the aero-brake levers and the cross levers. So far, so good. It was tricky getting the cable through the housing and into the cross lever. I needed to extend the cable out the the housing, and thread it into the cross lever, then slip the housing into place. I cut a section of housing to fit between the cross lever and the cable stops. I then slid the cable through, and connected it to the brakes, and rough adjusted them. I re-wrapped the handlebars. The tape comes right up to the cross levers.
Now comes the problem! The cable doesn’t slide through the housing smoothly enough. So when I retract the brakes, they engage. But when I release the brake levers, they don’t fully disengage. So I will probably take them apart again, and start over. This time I wont wrap the bars with tape until I got them working smoothly. Live and learn! :)