The overworld border is pretty limited to edit, especially because it's a fixed tilemap in comparison to e.g. the status bar, especially the super version. Because of that, I made this patch which enables you to edit at least the top and bottom part.
For a list with (in)compatible patches and codes and, check out this thread.
As always, the readme contains more information.
Request made by GreenHammerBro.
-Patching now displays on the Asar console window the RAM range.
-2019-12-19: now shows relative RAM address.