As you might know, doing the B4 shift servo update on 5-speed auto AW55-50 cars can be a little difficult because of the snap ring. When putting everything back together, you need to push down on the spring-loaded cover (1st hand), hold the snap ring (2nd hand) and hold the snap-ring pliers (3rd han...

Wow this car of mine has been gone for a long time, but I'm glad the trick worked for you!

You can push it by hand. The tough part is doing 3 things at the same time, necessitating 3 hands. I guess your method could work too, to hold the cover in place while you install the snap ring.