Subaru conversions are nice. I think you have a good starting point there for a project.
The hydraulic pump is almost always under the front hood/in the front trunk. It’s usually a cylindrical pump that’s a little bigger than a big coffee thermos. Somewhere fairly near that pump should be two relays that provide power to it. They might be shaped like cubes, but more often than not the builders probably used a pair of starter relays which look like cylinders (about the size of a D cell battery) with four wire posts sticking out. Usually you can get the top to open by using jumper cables to energize the big posts on one relay or the other. (One will be for “up,” one will be for “down.”)
Here is a picture of a typical starter relay.
Forgive me if any of that is overly simplified. I hope some part of it is helpful.