There is no official process to do this because the EVO solenoid should come on the new pump. Did your pump not have one on it?
Take a look at the picture below. This is how the pump should come with variable assist. I don't show an option for non EVO so where did you get this pump? Was it a used pump? Can you get a picture of it or the part number and manufacturer and I can see if we got the right pump?
Images (Click to enlarge)
Saturday, March 7th, 2020 AT 7:04 PM