make Outlook use alternate calendar
 

I have found a dll file which can be replaced by Arabic Hijri
Calendar dll files in outlook 2003 program folder (program
files\microsoft office\office11) in order to view the calendar in
Persian Solar Calnedar, however to make outlook use it as its main
calendar I have to change the "Regional and lang..." in Control panel
which changes the calendar of the whole windows into Hijri lunar
calendar which is not an ideal situtation :).
So how can I make outlook to use Hijri calendar as its main calendar
while the XP calendar is still Georgian?