Ah, okay. Here's my suggestion:
1. First, go to my guide at this link and follow the instructions for "Setup" and "Adding the Scenes":
http://forum.c-rpg.net/index.php/topic,1385.0.html2. Then, once you've made that module, place a copy of your map's .sco file into that
new module's SceneObj folder. Rename this copied .sco file "my_scene_20.sco" (assuming your map is a siege map. if it's battle, call it "my_scene_1.sco" instead)
3. Next, open the strings.txt file in the
new module, do a search for "my_scene_20" (or 1, depending on what you called it). Then in that listing, replace the terrain code with the terrain code you used for your map. My guide has a section on "Terrain Code" if you need more help with this step.
4. After you've done those two adjustments, you should be able to run that
new module, host a multiplayer game, and run map #20 to see your new map (or #1 if it was battle instead of siege.) Ta Da!!
NOTE: The whole 1 and 20 thing is because these mod files I made add 20 blank maps that you can edit in multiplayer directly. However maps 1-15 are set up specifically for battle/deathmatch and maps 16-20 are reserved specifically for siege. So you can use whatever number you please ultimately, as long as the .sco and the scenes.txt entry are the same number.
It may feel like a bit of work up front, but once you've done all this, any time you want to start editing a new map, you can just host a multiplayer game in the new module and pick one of these 20 scenes to start editing immediately and playtest.
Let me know if you have any questions!