[Hall of Famer]

I see. Hows your experience with Smarty so far? Converting old template system into Smarty template system should be easy, although you may encounter some issues using smarty's Smarty::assign() method if you aint quite familiar with OOP.

Theoretically three .tpl files should be sufficient for this script, one for the main theme, one for ACP theme, and another for the install wizard theme. Of course custom themes may define their own .tpl files, so the number may vary if we include old themes such as Green and Elements in official package.