It IS possible to roll crimp plastic shells but I am not sure your tool will do it... I just don't know. I have one too and they were made for paper hulls which were easier to deal with than plastic is likely to be. Some of the reloaders who load buckshot will likely come along and tell you how they do it.
Plastic shells have been factory loaded with roll crimps, from time to time but the process is a little more intensive than a pie crimp.

 

Plastic shells that is roll crimp is with heat of spinning the tool with a drill press is best to heat the plastic to get it to roll crimp.I was thinking of getting a tool like you have but i found out that you needed heat to make it work with plastic roll.You can get more info and a tools for it at Roll Crimping Tools-Ballistic Products

 

You can roll crimp with the "old" crimp tool....I have a couple of them and they work just fine...if you're using once fired shells trim about 1/4in off (which will be most all the old fold crimp) when you put the loaded hull in the crimper (don't forget the shot card ) rotate counter clockwise for a few seconds (this will "warm" the hull edge) then back clockwise with a bit of pressure, you'll feel when the crimp is done....voila', roll crimped shell...may take a few tries to get it "perfect"...but it's pretty easy...

 

Good tread, thanks