<partnerlinkbinding name="YourPartnerLink">
<property name="wsdlLocation">YourPartnerLink.wsdl</property>
<property name="basicHeaders">credentials</property>
<property name="basicUsername">myusername</property>
<property name="basicPassword">thisissecret</property>
</partnerlinkbinding>
Or using the http username password mechanism:
<partnerlinkbinding name="YourPartnerLink">
<property name="wsdlLocation">YourPartnerLink.wsdl</property>
<property name="httpHeaders">credentials</property>
<property name="httpUsername">myusername</property>
<property name="httpPassword">thisissecret</property>
</partnerlinkbinding>