Add one include in core - Joomla! Forum - community, help and support

hello,

i want add 1 include file in core
(application.php)
joomla 1.5 beta 2

include_once ( $mosconfig_absolute_path . '/joomfa/'. $mosconfig_lang .'_date.php'

how can add code joomla 1.0.x ,use in joomla 1.5?

for example can underestand :
require_once ( jpath_base .'/date/'. $mainframe->getcfg('lang_site') .'_date.php' );

but give me error :
fatal error: call member function getcfg() on non-object in d:\xampplite\htdocs\joomla15._beta2\26 may\libraries\joomla\application\application.php

or

require_once ("./joomfa_date_' .$this->language. '.php") ?>

the give me error :
fatal error: using $this when not in object context in d:\xampplite\htdocs\joomla15._beta2\26 may\libraries\joomla\application\application.php on line 905


please me

thanks

please me