Looking at this plugin in Motion, I think it does not actually use any features that were new in 5.3, so it *may* be possible to do a little trick, which consists of editing the transition in a text editor (such as BBEdit, or Smultron, or even TextEdit, but be sure to save as plain text, NOT rich text).
So, here is how you may be able to do it.
1) First, make a copy of the whole folder (e.g. "Rolling Zoom In"), for safekeeping, just in case something goes wrong.
2) Open the "Rolling Zoom In" transition file inside the above folder with BBEdit.
Near the top you will see this:
Change the values, so it becomes:
and save the file.
3) Open FCP X, drag a transition to an edit point in your timeline and see if it now works.
If this works, just do the same for the other transition.