I'll bet that you didn't think that cable routing was going to be such a big issue.

The cheap dirty solution, like chriskmurray said, is to run a continuous cable housing from the brake lever to the brake and zip tie it to the frame.

A more elegant solution is to buy a clamp on cable stop. I think that Problem Solvers is the brand name. After you find a source and price out the clamp on cable stop, however, zip ties are probably not going to look so bad.