Adding additional font-lock face to info files

[Angelina Carlton]

Hi, 
When reading info files, I would like to highlight strings that are quoted
by the author with `'

For example in the excellent book emacs-lisp-intro this snippet:
,----
| Both the examples just mentioned work identically to move point forward
| three sentences.  (Since `multiply-by-seven' is not bound to a key, it
| could not be used as an example of key binding.)
`----
The string `multiply-by-seven' is what I would want font locked.
Unfortunately I am not far enough into this book to learn how to do
this. :-) 

The only faces I see that I am able to customize are:
info-header-node                   info-header-xref
info-menu-header                   info-menu-star
info-node                          info-title-1
info-title-2                       info-title-3
info-title-4                       info-xref
info-xref-visited

Thanks!
-- 
-----Angelina Carlton-----
orchid on irc.freenode.net
     brat@magma.ca
   http://bzgirl.org
--------------------------