There should be a way within faces-config or some other mechanism to register EL
functions. Perhaps as a library, by function prefix, much like how Facelets tag
libraries are registered. Right now it is impossible to register EL functions
without wrapping FacesContextFactory with an implementation that returns a
wrapped FacesContext that returns a wrapped ELContext that returns a proper
FunctionResolver. And frankly I'm not 100% sure that would even work.
In addition, there is no mechanism for providing a "wrapped" FacesContextFactory
like there is for ViewHandlers for example. This makes this approach even more