Gamemodes automagically create a minigame from the settings in gamemode.txt. If your addon is a gamemode, you can simply use that, and reference it by $defaultMinigame.
A minigame is just a scriptObject. Create a minigame and do findClientByName("chubaka").minigame.dump(); to get a list of the variables used, then use new ScriptObject() { variable = value; }; to create one.