Help Using Nintex communicate with PSI

I'm trying to use a webservice to call QueueUpdateProject.  So far I haven't been successful and I believe it is due to the dataset that I am using.  Does anyone have an example dataset that they have used to update an Enterprise Custom Field?

 When I say not successful, I mean that I can run the webservice just fine, but the updates are not reflected when I go to that project and view the field values (they remain the same as they previously were). 

 I cannot use the built in Update Project Properties action because some of my enterprise custom fields are backed by Lookup tables, and this action fails when used with those types.     

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/office/project/server/webservices/Project/">
  < soap:Header>
  </soap:Header>
  <soap:Body>
    < m:QueueUpdateProject>
      < m:jobUid>guid</m:jobUid>
      < m:sessionUid>guid</m:sessionUid>
      < m:dataset>xml</m:dataset>
      < m:validateOnly>boolean</m:validateOnly>
    < /m:QueueUpdateProject>
  < /soap:Body>
</soap:Envelope>

Thanks