Okey, this is what I did to get it to work:
In your server module, open up scenes.txt.
Copy the strategus scene of your choice, for example Reyvadin (which will be used through out the example):
scn_town_8_walls town_8_walls 256 none none 0.000000 0.000000 100.000000 100.000000 -100.000000 0x000000013002491600055157000000d20000152a0000611a
0
0
outer_terrain_plain
Copy that line of code and replace one of the blank1-200 entries (use the ones after 20 (earlier might be in use)), like this:
scn_blank_49 blank_49 256 none none 0.000000 0.000000 100.000000 100.000000 -100.000000 0x0000000130000500400649920004406900002920000056d7
0
0
outer_terrain_plain
###
scn_town_8_walls town_8_walls 256 none none 0.000000 0.000000 100.000000 100.000000 -100.000000 0x000000013002491600055157000000d20000152a0000611a
0
0
outer_terrain_plain
###
scn_blank_51 blank_51 256 none none 0.000000 0.000000 100.000000 100.000000 -100.000000 0x0000000130000500400649920004406900002920000056d7
0
0
outer_terrain_plain
Now open up strings.txt and enter the correct name (correct name being the name of the scene), like this:
str_blank_49 Blank_49
str_town_8_wall Reyvadin
str_blank_51 Blank_51
The second name is optional, and is what will show up in the game browser.
In your server config, simply add "add_map town_8_wall", as a map, and you're ready to go.
Bit tired, hope that's a decent enough explanation.