Well, lets set basics first. The Compressor Bypass Valve (CBV) releases excess pressure from the intake tract which occurs when you are in boost, and then suddenly close the throttle plate.

You seem to be talking about the wastegate. This part regulates boost by allowing exhaust to flow around the turbo. This consists of 2 parts, the actual wastegate, which is a valve, and the wastegate actuator, which opens the valve.

Stock, the actuator opens the wastegate when it receives around 5 psi of positive pressure. Airflow to the actuator does not go into the intake tract, so if you have a pump applying pressure to the actuator, you're not going to set off any alarms for the engine computer.

However, what it looks like you want is to have 2 different levels of boost, is this correct?

What I would recommend is to find an actuator that works at around 2 psi. Then get some solenoids and a manual boost controller. This will let you set 2 conditions with an in-cabin switch:
A.) Pressure reading from the intake manifold will go directly to the wastegate, which will be your "low boost" setting.
B.) Pressure reading from the intake manifold will go through the boost controller, which will be set, say, at 7 psi. This means no pressure will get to your wastegate actuator until you hit 7 psi, so your car will make boost up to 7 psi.

You'll get the same results as simply not pressing as hard on your gas pedal, which would probably be easier to implement.

Greg