Typically you would process this with XMLTABLE · Teiid Documentation
Your context xpath will depend on whether the envelope/body tags are included. Assuming they are, you would use something like:
... from xmltable('/*:Envelope/*:Body/MySoapResponse/MySoapResult' PASSING doc COLUMNS TAG4 string, TAG5 string) x
Where doc is blob/clob/xml value for the document passed from the webservice invocation.
Teiid Designer Teiid Tooling - JBoss Community should also be able to assist in generating the sql for these scenarios.