I don't quite understand what you are talking about.
We are talking about the Extended Soap service here, and all you need
to do is add the jar with the other plug-ins in the WEB-INF/lib
directory of your Jira installation. Then the service is accessible
from the url
http://your-jira-install/rpc/soap/sharedspace-s1v1
(including the original Jira Soap service methods it extends).
If you want to know about how to deploy your own Soap add-on, then I'd
have to point you at the Atlassian developer docs for accurate
information, sorry.
If you would like a service method added to the Extended Soap Service,
you could just ask, and I can add it for you... (sourcecode should be
provided and be open/free ofcourse)
HTH