Intercepting onFocus event in Outlook's Appointment Form

Question

Hi,

I'd like to control Localization value (comboBox) on the form. This is how it should work: when a user clicks on the comboBox, a window with defined values appears. Then he accepts and chosen value from the window appears in the localization field. I'm wondering how to realize it. I thought about win32 API and monitoring events, but I don't know how to do it. Please help me!

Thanks,
xaze