You can check out the Axis Group blog post regarding the Python integration with AAI (http://www.axisgroup.com/qlik-sense-server-side-extensions-part-13-architecture-environment/)
They have explained in detail how the data is passed from Qlik to Python and visa-versa. Once you understand this you can do the usual scripting in Python as you would have done working solely in Python environment.
Axis group guys have done a youtube video to demonstrate their AAI project. You can check that out here (Dork Cast Episode 1 (Advanced Analytics Integration) - YouTube)
I hope this will give you enough knowledge to work with your predictive models in Python and Qlik.