If you use jboss 4.0.4+ with EJB3 then there is a very easy way to create a webservice: use annotations on a stateless EJB.
Also in this case you can use (WS and EJB3) :
jboss IDE eclipse Betat2 (all plugin are already on)
and sdk 1.5 (not the 1.6 you could have problems with)
and you can follow this tutorial :
but stop before client...