We need to review how the Renderer works e.g. the IceFaces Seam Mail compatibility issue - so keep an eye out for this!
I guess if people are starting to need to use Renderer outside of JSF, then we should create a org.jboss.seam.facelets package with a Renderer class that can use non-JSF resource loading, and have org.jboss.seam.faces.Render extend it and override its resource loading to use the JSF ExternalContext.
Alternatively, we could just change the implementation of MockExternelContext, but that seems a bit dirty, and it's kinda wrong to be using the org.jboss.seam.faces package when you're not using JSF...
It's worth a feature request in JIRA.
I'm not quite sure what you mean - how can we use facelets outside of JSF?
What we need to be doing is building a fuller JSF environment in which to execute the render.