Cheating, primarily. Modding can be used to cheat, but we're not discussing anything as advanced as that here (i.e. no changing satisfaction thresholds, group sex chances, farm training results, trainer effects, etc). Just the girls, MC and the brothel.
_BK.ini indeed controls a girl's stats, so you can slightly cheat that way. But the .ini files are still processed by the game, and the returns are not great. First, there is no guarantee you'll even find the girl whose .ini file you just changed. And second, there are clear limits to what you can accomplish that way (traits and personality are the strongest, I think, since you can set them to be non-random).
Cheating does not differ very much between 0.2 and 0.15b. Most of the underlying data structures are still the same, and can be changed in the same way. I figure MonkOne's trainer might even be straight up usable for 0.2.