the one you're thinking of is setModPaths(getModPaths()); but all that does is allow you to update zip files without rebooting your game.
what you want is exec("path/to/server.cs");
for example: exec("add-ons/event_daycycles/server.cs");
note: this will only work properly on add-ons without "content" which is basically models.
guns = no
events = yes