How can I automate an update of the outlook.hol file?

[schse01]

I would like to add a custom holiday to the outlook calendar for all my users.

I have modified the outlook.hol but I would like the information to be
loaded into all my users calendars without having to ask them to go into
outlook, click tools, click calendar options, click add holidays, etc etc.

I can copy the new outlook.hol file to users PC's via logon script or
similar, but does anyone know how to automatically have the new file imported
into Outlook without any user invervention?

We are using Exchange 2003 with Outlook 2003.

Any help would be greatly appreciated!

Thanks
Seb