A naturally aspirated engine can be supercharged by installing a supercharger onto the naturally aspirated engine.
However it's not a simple process and you can't just simply install the supercharger on the naturally aspirated engine and expect it to work.
Besides adding the supercharger you'll also need to change your engines compression ratio, ECU mapping, and fuel delivery.
That is to make sure the engine is getting the correct compression ratio, the proper amount of fuel delivery and the proper ECU mapping of the engine.
It's hard to describe exactly what is needed through text but it can be done if you study up a bit on how to actually get the supercharger working on the naturally aspirated engine.
Adding a supercharger to your engine can also sometimes decrease your fuel mileage so I would not recommend adding a supercharger to your engine unless you really need too or want too.