With the release of DevTest 8.2 earlier this month, support has been added for SOAP with attachments in CA Service Virtualization. This How-To blog will cover this topic. The WS SOAP protocol data handler has been updated to support SOAP requests with attachments.
See attached doc that uses SOAP UI to make calls to a public service first and then record use DevTest recorder and then plays it back.
Let me know if you have any questions.