Unlike the v2 version of the updatecenter, the v3 version does not support
post-install or pre-remove processing.
While many of the functions that would require this can now be handled with OSGi
(with proper versioning), some cannot - for instance, modification of domain.xml.
Without support for this feature, the updatetool is simply a file delivery
mechanism, not an update mechanism.
I've spoken to the updatecenter2 team, and they tell me that this is a product
specific feature, and they will not be providing this functionality.