using Ruby handsoap craft AuthHeader

Question

How would I go about adding an authheader to the soap header of a request using handsoap?

so for example I want:

<soap:Header>
    <AuthHeader xmlns="thenamespace">
      <userguid>xxxxxxxxxx</userguid>
      <userkey>yyyyyyyyy</userkey>
    </AuthHeader>
</soap:Header>

thanks in advance for any suggestions or direction - haven't been able to track down anything in a sample or documentation explaining how this could be done.