Go to eoserv.net -> downloads -> Eo Map Editor 0.3.1b.
When downloaded, copy and paste the GFX of EO, EE, BU, FE, etc. (Pretty much whatever GFX you want to pixel in) into the GFX folder and then just open the map editor file.
To start mapping, go to file -> new and then just set your map width and length.
There's tips on mapping on the eoserv website.
I'm only here for the food.