buck-boost

Hi, I am using a buck boost converter MC34063 to bring 14.8 V from four Li Ion batteries in series down to three different voltages 12V, 5V and 3.3V. I am planning to use the step - down converter given in the datasheet (image below) to do this but specifically how do modify the circuits...

For a circuit I'm designing, I want to use an MC34063AL-D08-T DC/DC converter (or a similar one; I just need a through-hole package) as a boost converter to boost a voltage \( V_{in} = 3.3-4.2 V \) (coming from a Li-ion battery) to a stable output of \( V_{out} = 5 V \), with \( I_{out} = 250 mA...