Wellhead control line deployment involves replacing the seat/retainer plate of a master valve of the wellhead with a modified retainer plate. The retainer plate defines a first port communicating from a central opening of the plate to outside the plate. A modified bonnet installs on the master valve, and the bonnet has two ports, one communicating with the first port in the retainer plate and the second communicating with a needle valve port. The communication ports are linked by a tube with outside diameter seals that inserts between the retainer plate and the bonnet. A control line hanger can be retained by locking into an adapter sleeve or directly in the back-pressure valve threads of a tubing hanger. The adapter sleeve can be attached to the retainer plate or have a collet to snap into the back-pressure valve threads of the tubing hanger.