it's not possible to change the security-domain from "other" to another one for soap-services.
I've tried the example switchyard-quickstart-demo-policy-security-wss-username and changed the security-domain in jboss-web.xml.

i've tried the switchyard.xml variant to:

<sy:domain>
<sy:properties/>
<sy:securities>
<sy:security name="apo2" securityDomain="apo2logins" rolesAllowed="AFA_Administrator"/>
</sy:securities>
</sy:domain>

and put my services to this policy like:

<sca:service name="SalespartnerImporter" promote="SalespartnerImport/SalespartnerImportEJB" sy:security="apo2">...