Sign outgoing WSS with xmldsig-more#sha256-rsa-MGF1 ?

Hi,

I need to sign an outgoing WSS with xmldsig-more#sha256-rsa-MGF1 (http://www.w3.org/2007/05/xmldsig-more#sha256-rsa-MGF1).

As this Signature Algorithm is not available from the dropdown menu:

Is there a way to add it manually to SOAP UI ?

Thanks!

Cheers, Alex.