How do you call a package from XML?

Can anyone tell me how to call a package from XML or advise me on the best way of achieving the following?

I want my XML to call a  package that will do all the work and create a temporary table that will then be used by the SQL in the XML will retrieve the data.

I've tried setting up an Object, Type & Function and using PIPE ROW.

That works fine for everything I've tried until now.

However for this report I really need to write to a table within my package or function. That is causing me a problem as XML doesn't like that for some reason.