dynamically creating items

System

In my datacapture.cfg file i have an item using a visualformat textarea. I need to be able to change the configuration file that visual format uses in this textarea based on a selection that the user makes in another item (a drop down list). I can use form api to register an onItemChange event to capture when the drop down list changes but how do i then get it visualformat to change the configuration file it uses? can this be done?

Thanks!

Shaheed