Thx for the help, I didn't I don't have an effect called 'SCREEN' but I got allmost what I wanted by using 'BLEND' and 'COLOR REPLACE' sadly though it didn't looked good enough.

So I dragged my feet over to AE just so I could start spending time finding out what AE uses as a replacement effect for PPro's 'CROP', but in the end I managed to do what I wanted and now it looks like it's supposed too

and a picture for the curious of the different results.