Did you get any help with this Katherine? I have the same problem.
had this same issue. following works for me.
-create a dataconnection to the db with a random query to the table.
-just clone the dataconnection
oDConn = xfa.sourceSet.DataConnection.clone(1);
-change the query attribute to the stored procedure
oDConn.resolveNode("#command").query.select.value = "exec spEmpApp 'parameter'"
-open the cloned data connection