Dan:

Run the housing through the 'glass at the point you want it to exit and just epoxy the housing in place. Make sure you get an amount inside, because after it hardens you'll trim the housing flush. Then leave the push rod out until the bird is painted.

If you have the control horn inside, totally concealed, knock out a "Former" to fit inside the boom, epoxy the housing to it, then smear epoxy on the former and use the pushrod housing to push it into place.

HTH

Bill.