For this, I believe you would need to use the build in Steam Workshop downloads on the Easy Setup page and then add this to your server
http://steamcommunity.com/sharedfiles/f ... =135509255
I wasn't able to find an SVN, so it is worth giving this method a try. Once you have it added, you will need to restart your server for it to be downloaded onto it. Also, you will need to add a Lua script that will force clients to download this addon as well. After it has successfully downloaded, you will need to specify the server to start up with this gamemode, which is also available in the Easy Setup page. This was brief, so let me know if you need clarification on anything.