2 options:
Easy: make a grinder that does your gathering loop and add that mob to the kill list
Harder: In a plugin add a state which is at a higher priority than gathering. Have a look at the grinder example bot project that droidz posted in the tutorials section on how to make a product. This should show you how states are added to the engine and an approximate priority you should make your state.
There's a little bit of info about states at the bottom of this post too but you'll get the majority of info from that example project.
edit: link to droidz example
