1. Type in the server you normally join (i.e. play.dungeonrealms.net)
2. Select the types of waypoints you want (i.e. no spawn, only major, etc)
   
3. Click Download, and locate the downloaded SERVERNAME.DIM0.points file
   
4. Drag the file into either...
   %Appdata%/.minecraft/mods/rei_minimap (Windows)
   /Users/USER/Library/Application Support/minecraft/mods/rei_minimap (Mac)
   
5. Open Minecraft. If you didn't select for waypoints to be visible by default, press [m], click Waypoints, and enable any you need.

I normally respond within a few days if you provide a valid email.