Can substvars be used for general variable substitution?

[Jean Pierre LeJacq <jplejacq@quoininc.com>]

As part of the wn packaging, I'm parameterizing the source code
with variables that define the location of directories and files
(similar to the way the inn source code is distributed).  For
example, the man page for wn is parameterized on the location of
the html documentation where the variable @@dirdoc@@ is replaced
with the actual directory:

   file wn.8.in

   .\" MAN PAGE
   .\"
   .Dd January 7, 1997
   .Dt WN 8
   .Os Debian GNU/Linux
   .Sh NAME
   .Nm wn

   This documentation is incomplete.  The @@dirdoc@@ documentation is the
   authoritative source.

It's simple enough to write a script to do the variable
substitution myself but I would like to standardize on the dpkg
utilities.  Is there a way that I can use the substvar facility
in dpkg to accomplish this task?

Thanks,

-- 
Jean Pierre