Hi Aurelien,
you can use jboss-webservices.xml for context root & request path customizations.
See the following documentation on how to migrate:
https://community.jboss.org/wiki/JBossWS4MigrationGuide
In order to customize your context root
from 'myApp-ejb' to 'myApp-myApp-ejb/ see section
jboss-webservices.xml descriptor