I've also got a mouse interface lying around here, I think it's a Punchinello Mk I. Allows connections of serial style connector PC mice. It's a little grey box which connects to the Amiga mouse port and there's also a second device which in turn connect between the grey box and mouse port and also connects to the parallel port. I think that is what gives you scrollwheel support.
Mind you I've never used it, so I could be mistaken.
