First, move your .BSP from main/maps to main/maps/mp after compiling.

Then create a shortcut to your game's .EXE file, and modify the properties to:

"C:\Program Files\Call of Duty\CoDMP.exe" + map brutus_battle_map + set sv_pure 0

where brutus_battle_map = your map name

Then use the shortcut to launch the map directly.

If you want to see tris and such, change the properties to:

"C:\Program Files\Call of Duty\CoDMP.exe" + devmap brutus_battle_map + set sv_pure 0

For tris, in console type:
/toggle r_showtris

type it again to clear tris

for r_speeds:
/toggle r_speeds

Again, type again to clear.