Welcome Randd,

I think you are wanting to compress the spring on the guide rod. I've used a thin punch thru the side of the frame. To "cage a spring" on the rod try some 10# fishing line around 6 coils; compress spring; tie of the fishing line leaving long ends. Assemble spring rod assembly, and clip the line to break free. Where safety glasses.

You could contact Walther for the plastic gizmo (I've never seen one). Was the P22 imported by Smith & Wesson? might try them.

 

I have a P22 22LR and I have the piece that you are talking about but I have had that pistol apart several times and put it back together without it. Takes a little practice and you gotta hold your mouth just right and it'll go right back together. I honestly have never used that little tool.

 

If it is a problem (my old hands don't work well any longer), they sell a "caged" spring/guide rod assembly.

It is American made, stainless steel $18, Galloway Precision Products.

https://gallowayprecision.com/walther/p22/stainless-steel-guide-rod-assembly-for-walther-p22/

 

If this is the usual push the spring and the guide rod through it's hole in the slide and capture the guide rod in a barrel lug, I generally lay the slide, open side up, grasp the guide rod with thumb and forefinger and push the guide rod through it's hole in the slide while my other hand controls the slide.

My CCW however, has a very stiff spring and guide rod so I hold the slide vertically at the edge of my work bench with the guide rod hole overhanging the bench top. Grasp the guide rod with thumb and forefinger of my strong hand and push the guide rod down to seat the guide rod through it's hole in the slide. My weak hand encloses the slide keeping the recoil spring from buckling while my strong hand does the work.