Hmm, maybe I should make a readme? OK, this assumes you are working with Windows XP. If not, I make no guarantees of its working. Anyway, download the executable. Unzip it to some easily accessible directory. Copy your CK savefile to that directory. Now go to Start->All Programs->Accessories->Command Prompt. Change to the directory you've installed it in. Type
Converter <MyCKSave.eug>
You should get a bunch of text output, and at the end it'll have made a file called "convertedMyCkSave.eug", which you should put in your EU2 savegame folder.
Now, this won't tell you much about the actual algorithm; that's what you need the source code for. The code in question is a little spread out; I don't know if you've done any programming, if not you may find it a touch tricky to follow. But anyway, the relevant methods are addCulture, beAbsorbed and getCulture in the class Country, to be found in converter.java.
Converter <MyCKSave.eug>
You should get a bunch of text output, and at the end it'll have made a file called "convertedMyCkSave.eug", which you should put in your EU2 savegame folder.
Now, this won't tell you much about the actual algorithm; that's what you need the source code for. The code in question is a little spread out; I don't know if you've done any programming, if not you may find it a touch tricky to follow. But anyway, the relevant methods are addCulture, beAbsorbed and getCulture in the class Country, to be found in converter.java.