3) You could also hook in a little bit later then what you'd do for 2) and modify the jbossws spi metadata that are created after parsing the webservices.xml descriptor. To be honest, you'd need actually create them most of the time, given it's not that common to have webservices.xml for JAXWS deployments. Btw, there's a little bug I just discovered here, I'm going to fix it later today or tomorrow.
Actually this would be better then 2) because you could *add* stuff over metadata info coming from a webservices.xml a user already provided.