Works for Nestopia 1.40, FCEUX 2.2.3 and 2.6.4, mesen 0.9.8, mesen 0.9.9, and mesenRTA.

I place this in the livesplit folder Resources/Splitters (which I think I just made). You have to manually add it to the layout as a component by going to Edit Layout/+/Control/Scriptable Auto Splitter.