Take some photos.

What kind of brake levers are you using?

Are you talking of the releasing of the wheel when doing maintenance, or typical opening/return of the brakes during use?

Campy puts their brake release at the brake levers. Several of the generics (aero, non-brifters) such as Tektro have an option of brake lever release too. Finding a good place for barrel adjusters could be tight, but there may be alternative positioning.

I would think that after a few weeks of zip tying the cable housing to the seattube, it would naturally take that shape, and one might be able to dispense with the zip tie.

Thinking a bit outside of the box. Some of the old Mixte frames would use a bottom routed brake cable.
http://www.bikeforums.net/bicycle-me...xte-frame.html


Sheldon Brown shows a similar "hack".
Installing and Adjusting Caliper Brakes


Anyway, perhaps a radical change in your cable routing would be worth considering.

Oh, keep in mind, a downward loop of cable housing can trap moisture and lead to a premature demise of cables and cable housing.