Ok. Updated the title.
Thanks! The original mod is under GPL3, so you're not moving on a legal minefield here, but avoiding ambiguity is generally a good thing.
I hope this is just temporary until the original mod author can update it to support what i need.
In case he does, you should also think about how to remove your mod (unless you want to fork and implement more changes) because there's really not much use for different copies of the same mod around. Here is a forum thread on this topic. But that's just my opinion, you can do as you please, of course! :-)