The minimap isn't really manipulatable that way. You could for example create destructables with specific colors and as the cartography but it'd be extremely hard to do right for the most part. It really depends how complicated you want it to be I guess. If your looking to make ^ type mountains and whatnot that is do-able but it'd take at least 4-5 destructables probably with very specific placement and then the terrain would have to match it. Don't get me wrong though the idea of adding cartography sounds neat; just how to implement it sounds a bit of a harder aspect.
For the rpg i'm making I was planning on including an side minimap that had an showing of where you've traveled in relation to the start since it's generated in 64 by 64 areas a bunch.
(Imagine an 10 by 10 for example area where each square represents a 64 by 64 area that you've traveled through marking where your currently at and it has directions. It also marks whether the area is forest, dungeon, town, or unexplored.)
But this gives me some ideas on maybe how to change it up a bit. I'll give it some more thought i guess.
Edit: Also you cannot really change the ping buttons or minimap buttons at all besides how they look(players can still click them no matter what). It's just impossible to change them for some reason. Maybe you can change the ping model though and have the game ping locations ahh now theres an idea. I guess some testing would be in order to see how accurate pings can get though. Also this would make the minimap a bit more workable for cartography in a sense. Though I don't think there is an event to check for if a player made a ping. . .
Hmm I wonder if hoverable trackables fire when they are moved over even within the minimap. -> Nope
Well, targetable spells can still use the minimap tho they are subject to targeting units or destructables instead of their location which may/may not adjust their accuracy.
Ok, I'll try to implement it for the dungeon master type player for my map I guess using the targetable spells method in some way. There are some issues i'm having with terrain generation mainly- destructables when created leak handles, and terrain deformations are unusable because they are a permanent leak.