>> How can I 'teach' cc-mode about new access keywords?  In other words, in
   >> addition to the usual "private", "protected" and "public" I also want to
   >> add "signals" and "slots" each of which can be preceded with an
   >> appropriate access level.
   >>
   >> Does anyone have a clue?

   R> http://www.emacswiki.org/cgi-bin/wiki.pl?QtMode

I am pretty sure that this is obsolete.  cc-mode no longer has the
c-access-key variable.

I haven't actually done this, but it seems like the description in cc-langs.el, along with the above reference, should give you enough information.