Hi!

I'm in a situation where I want to use the master version of css-mode,
but I want to stay at Emacs 24 for all other purposes. This can of
course be solved by copying css-mode.el into my local Emacs
installation once in a while, which is what I've been doing so far.

However, I imagine other users may in the same situation as me,
especially since the master version of css-mode now provides a whole
new scss-mode as well.

I think it would be very convenient to be able to subscribe to an ELPA
version of css-mode, which could be updated more frequently than Emacs
releases. Is there a procedure for turning a built-in mode into an
ELPA package, and at the same time keeping the built-in package? It
looks like for instance ada-mode is in a similar situation.

-- Simen