First of all I still stand by my advice at
Re: When to use Tie, don't use
tie unless Perl's syntactic design choices are getting in your way.
That said, the connection between tie and OO is very simple. Provide the right OO interface for Perl to talk to, and Perl will let people use the tie mechanism to make a (variable, array, hash, whatever) be implemented through that interface.
If that comment confuses, then the example at RE (2): Filehandle Filter may enlighten. Just alias the methods that Perl is looking for to methods that a human would think of, and suddenly what was a tie interface becomes a reasonable object to use directly with OO.
