I don't have any experience with Qualys but my general recommendation for all unsupported data sources is to see if ODBC is a possibility. If you are unable to find anything, perhaps searching their community might uncover some info you can bring back here.
Hello Kevin - Did you make any progress with your project? I am trying to complete the same process and I wondered if you were successful.
We don't have any sample code for Qualys but it does look like they have some APIs (Community: Developer | Qualys Community ). Assuming the data you want is available in their API you should be able to use the Tableau SDK to create extracts (.tde files) or you could also write a Web Data Connector.
I have the same need. Were you successful it getting this to work with the Qualys API?