Doesn't work perfectly for subplots but...
I managed to get it to work reasonably well (on 1 occasion with an Area subplot) by...:
1) - Open gridLegend .m file and comment/delete line 273.
2) - If you are getting errors about Scribelegend, delete lines 278-284
3) - Specify a location (I used 'location','southoutside' )
Basically the issue with subplots (from what I can see) is that gridLegend is trying to control the 'gca' which doesn't seem to exist in subplots.
Complicated to get started with the java files etc and no very good instructions on this. See the example however.
Doesn't support specifying to a range.
However - support multi-dimensional variables which is a great bonus.