At the moment there is no support for configuring a watch face.
From what has been described previously by the folks at Garmin, we are expecting to see an update to the Garmin Connect Mobile app that will allow users to configure properties for applications. Once this is put into place, I think you'll see a lot of user controllable settings being added. One of the watch faces I just recently submitted already has code in place to allow the user to select a color scheme and a bunch of other settings.