It is possible, but I haven't tried it.
If you go into the LA mod v2.1 folder and open maps then you should be able copy the 3 files named 'freeplay.dds', 'freeplay.e4m' and 'freeplay.eft' and rename them to 'multiplayer.dds', 'multiplayer.e4m' and 'multiplayer.eft' respectively. Make sure you back up the current stuff called multiplayer and it should work. Many of the functions of 'to station' and similar won't work as they are disabled if the scripts recognise the game type as being multiplayer. Still, give it a shot and let me know if it works out for you.
You may need to make some edits on the map, but this should at least get you started in the right direction.
Hope that helps
I have begun working on a new project.
If you want in, PM me and let me know what you can bring to the team.
(Modelers preferred)