C1Scheduler can be used along with C1.Silverlight.Theming themes. The only limitation of C1Scheduler comparing with other controls is the next:

You should explicitly set C1Scheduler.Theme property to the theme ResourceDictionary. For example:

C1Theme theme = _new C1.Silverlight.Theming.WhistlerBlue.C1ThemeWhistlerBlue();
ResourceDictionary themeDictionary = C1Theme.GetCurrentThemeResources(theme);
sched1.Theme = themeDictionary;