Shouldn't be too hard, it can all be done by events. Here's what you do:
Make a new image, just a tiny red dot or arrow or whatever. This will be your indicator. Make it literally big enough to see just on the map.
Once done, import the picture.
Whenever entering the World Map from a town, you'll want to set up an auto-event which displays the picture of the indicator over the top of the map, in exactly the right place on the map to show where you are. So, this would be initially hard as you would need to find the x and y coordinates exactly for where you are on the map, (bearing in mind that the very bottom right pixel is (640,480), so say you were in the right-bottom hand corner of the map, you would want to display your indicator on coordinates (610, 460), roughly.) But once you have done that, you should get the image of the map always being there, and wherever you are on the map after exiting a town and entering the World Map, a red indicator should display. The only hard thing here is finding the exact right coordinates, so you're going to have do a lot of fiddling around with that.
You could also use the indicator type thing for towns as well, but make them white.
To get the indicator to scroll up, down, left or right as you move those respective directions is relatively easy, too - you'll want to imagine 'invisible borders', as it were, between, say, every 15-20 squares across your map. They would have to be exactly the same size each. So, in a sense, you are mentally dividing up your map into squared areas. To divide these squared areas, you will need a row of events. These would mark when one area starts and the next begins. Upon reaching the end of one area on the map, your indicator being in, say, position (520,460), as you approach the events, the indicator should shift a couple of pixels in any way you direct as you pass them. I know this hard to understand just reading it, so I'll show you screenshots of what I mean.(don't worry if the mini-map looks stupidly drawn, I did it in a hurry):
The mini-map with indicator in action:
http://i27.photobucket.com/albums/c187/ ... rshot1.jpg[/IMG]
The squared area of events: (see what I mean? These would be all over the world map, dividing everything)
http://i27.photobucket.com/albums/c187/ ... rshot2.jpg[/IMG]
This would appear as when you pass over, the indicator shifts just a tiny bit. repeat this all around the world map, moving it just one or two pixels in any direction. The only problem you might have is lag - slower computers might not be able to process movement well with so many Good luck!
I think that's about clear, if you have any other problems do ask me and I'll see if I can help more.