Since this thread was last updated, and long since the document referenced was written, that ability has been added to the solution outlined in post #6 on this thread.
https://wiki.asterisk.org/wiki/display/AST/Asterisk+16+Application_Dial
PS it is not a good idea to add questions onto very old threads. It is unlikely that your problem is really the same, and threads created now will not allow this to be done without moderator intervention.