Creating a command map
Command maps are created by using the mapshot command from the game. Check the mapshots page for more information. Once you are happy with your command maps they are specified in the playzone_commandmap entity.
By default a mapshot will create an image of the full 40960 unit bounds of the map. This is the image to be used by the OOB (out-of-bounds) command map. To make your own OOB commandmap, look in the SDK folder for base/commandmaps/oob_warning_template.psd. Copy your mapshot result into the layer above "for_Slipgate" and save your oob command map.
Since the playable area is 32768 units we only want to keep the inside 80% of the image for the regular command map. Within Photoshop the canvas size command (Image > Canvas Size) is used to crop the image. Be sure to set the anchor to the middle of the image and make the new size 80 percent.