Force namespace prefix in request

Hi! I'm using cxf (2.2.10 version) as a WS client. The nasty server side
implementation (I can't change it nor suggest to change it to his owner)
requires:

<blah:hola xmlns:blah="http://lalalala">
..................
</blah:hola>

and the (correct) payload generated by my client is

<hola xmlns="http://lalalala">
..................
</hola>

("blah" can be whatever I want)

I played with the package-info.java file adding:

@javax.xml.bind.annotation.XmlSchema(
namespace = "http://lalalala",
elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED,
xmlns = {
@javax.xml.bind.annotation.XmlNs(prefix = "blah",
namespaceURI="http://lalalala")}

but it does not seem to work.

Could someone help me?

Thank you very much

Best regards!