It can be done

Basically using an amal valve to give you a switchable bypass of the vacume hose connecting to the dump valve.

However it gives you the same effect of having a dump valve plumbed into your system but without the vacume hose attached. I guess this means you dont get the positive pressure closing the valve when the car is on boost. When we did it we didnt notice any problems but its something to be aware of - you might have to get clever with some kind of boost switch that turns the amal valve on when the car is on boost to keep the pressure in dump valve while on boost. Then turning it off before the car comes off boost so that there is no vacume to open the dump valve.