Well see here is the issue. You can not change an integration without being aware of the upside and downside of work that needs to be done. You users would need to be moved from the old integration to the new which means currently the only way to switch an integration that I am aware of is to switch from a standalone gallery or another forum product to vbulletin with the gallery. That is because vb
has an import script that imports other forums or photopost users into there product. Once one does that they can follow the rest of the steps to switch an integration.
There is discussion on this here that has the full steps you need to do. Switching from phpbb to vbulletin