Thanks for raising this, Paul. I think it's an extremely useful idea and have raised a JIRA for it.
I think the work needs to be done in two stages.
First, we need to develop a better API for the driver class TestScript which performs the offline typecheck. It currently only exposes a main routine which reports outcomes by printing to System.out and System.err. It would be better if the outcomes were reported via a structured data value.
Second, we can then concentrate on developing a maven plugin and an ant plugin to drive this API.
Of course the second task will need to be thought about first because the API will need to conform to the expectations of maven and ant plugins. However, this division of labour also relfects a division of expertise since all things Byteman-specific should be hidden under the API whilst all things maven or ant specific should only reside in the plugin code.