If I power my micro from a 9v battery. Can I wire the 3.3v output and the 5v output in series to get 8.3v output? Looking for a way to get regulated output. Thanks.
The short answer is "No", the 3.3V and 5V output both have common ground so can not connect in series.
Use a step-up/boost converter, then adjust trimmer to specific voltage you want.
Check out MC34063A chip.