Once you save something to your Sonos favorites, you should be able to use the playPreset() command with the numeric ID of the favorite/preset (eg. 0, 1, 2, etc) (example)
Once you save something to your Sonos favorites, you should be able to use the playPreset() command with the numeric ID of the favorite/preset (eg. 0, 1, 2, etc) (example)