How much shorter could a short cut be than pressing the # key? If you mean a short cut for inserting pre-defined comments, possibly with some variable substitution, you could use something like (X)Emacs Skeletons and Auto-Insert, cpp, or Devel::PreProcessor. Except for such basics as copyrights, rcs or sccs ID keywords, I would think that a short cut for inserting comments would be rather useless, as there has to be some thought as to their contents.