getComponent() should work with xe:switchFacet in the same way that getComponent() works with a panel.
[Other controls implementing NamingContainer, like the repeat control and the custom control component, will interact with the getComponent() method so that you may not be able to find child controls within that area. However the Switch Facet is not a NamingContainer, so it should work fine with the server-side JavaScript getComponent(String:id) method.]