JSF 2.0 improved the definition/handling of the instantiation of the FacesContext allowing non-servlet environments to wrap the base/core impl. This was done because most of the FacesContext apis are inherently runtime environment neutral – allowing the portlet bridge to not have to duplicate/reimplement and maybe get wrong base core function. Unfortunately MyFaces doesn't conform to this change and hence the Portlet Bridge can't run in the MyFaces environment.
Basically the bridge expects to be able to delegate from its FacesContextFactoryImpl.getFacesContext and then wrap the returned FacesContext with its own. This requires the underlying core impl to be runtime (servlet/portlet) neutral during the creation process. The bridge will wrap the FacesContext and supply its own ExternalContext such that any servlet dependent impl in the core FacesContext/ExternalContext will be hidden by overrides.
FYI ... until this is addressed I can't begin any testing of the bridge on MyFaces.