Save Outlook folder in .pst via Visual Basic

Hi there,
I'm using Outlook 2003.

I need to save a folder in my outlook account, exactly as I do using menu file--> Export/Import, exporting it in a .pst file, but I need to do this via Visual Basic (cause I have to do this everyday on different PCs).

Which object should I use and which command?

I can't find any suitable command for the "object"
Set myOlapp = CreateObject("Outlook.Application")
Set object = myOlapp.GetNamespace("MAPI")
Set source_folder = object.Folders("Cartelle personali").Folders("Lavoro")

Is there anyone who could please help me?
Thanks in advance