m4_patsubst equivalent of: sed -e 's~(~%28~g' -e 's~)~%29~g'

Is there an m4 macro in one of the autoconf m4 libs that can do 
two substitutions like?:

    sed -e 's~(~%28~g' -e 's~)~%29~g'

or does this require calling m4_patsubst twice with nesting and
perhaps m4_pushdef / m4_popdef?  I want to do this substitution on the
expanded results of another m4 macro.

In general is there a suggested approach to this, without resorting to 'sed'?

--
thanks,
Tom