I'd spent some time playing with other methods but had little success bar altering damage levels and stack size. I think that event might be the answer, though my new arrival to Java and Forge leaves me uncertain after a good few hours fiddling with it and trying to implement anything.
The problem I'm having is that I can't get the event itself running, more because I don't fully understand its operation even after reading the javadocs, intro to Events on the Minecraft Forums and the code itself.
I'm getting there the more I play with code and test various functions ingame, I could just do with a little push on the usage of this particular event. I'm sure it's something glaringly obvious staring me right in the face...
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Edit:
I eventually managed to get something working by reworking some of the shearing code, though it was incredibly sloppy and would never be suitable as it was. My understanding's growing at least, and I can see now how to use the event to my advantage. Thanks!