Can't go wrong by putting a copy of the mll file in each of the SCRIPTS or PLUGINS folders you find. Maya feels the need to put three of these folders in different places. Why? I have no idea. But if it doesn't work in one of those, try all of them. One of them should work.
Dave Baer
Professor of Digital Arts
Digital Media Arts College
Boca Raton, Florida
dbaer@dmac.edu