The transisition in most everyday turbo vehicles is not as sudden as your explanation suggests. Boost usually gradually builds up along with your revs.

Only the largest turboes feel like they are cycling on and off because of the amount of exhaust needed to turn the turbines.

There are manual boost controllers that can elevate the wastegate's opening pressure. I'm not sure if you can indeed control boost. You are still at the mercy of how much exhaust is passing through the turbine.