As far as I’m aware, the properties that the Steam server list uses are these:
ServerName
MAPNAME
(they are case-sensitive)
As far as I know, the ServerName doesn’t actually work and you have to add
-SteamServerName="Your server name here"
to the shortcut that you use to start the server.
There should also be a setting for passwords but I haven’t figured that out yet. As you said, there is no information out there.