I ran into a similar problem, some time ago. Although I did not need the minimap itself, for entire TOWNS, I think it could be solved in a similar way.
I wanted some of the icons from the tileset, to show up on events with the minimap. Simple problem, easy fix. I took the individual tiles, created character sprites for them, and added them into events. Took me about 30 seconds to make the needed events, and they show up on the minimap without problem. Rock, stump, bridge, etc.
This only worked in my case, but if someone were to categorize areas of a map based on the x and y coordinates, in groups. This would be quite an interesting patch for this minimap indeed.
Buffet Bushi: I gain power with the belly slaps! *slaps belly*
Everyone else: ... Something is wrong with this guy.