After many hours spent looking for decent examples on how to use the bouncy-castle set of libraries, I found the cwguide and was able to progress further. I decided to include the results of my findings in an "all included Main3 class". So here is the code.

The examples are in the org.sniggel.examples/Main3.java

I have also included a PDF and source code for cwguide, which are in the resources folder and cwguide package respectively.

I use buildRootPrivCertLightV3 and createPKCS12File functions for now. The other are samples.

Hope it helps somebody.