I need to know how to draw text with UnicodeFont and Slick. I don't want to make a class that extends by BasicGame or BasicGameState, I just want to implement it straight into my main-class. Thanks.
Well, the JavaDoc of UnicodeFont, as located here, gives you a few methods called 'drawString'. Note that you don't need any reference to any of the other Slick classes.
Now, if that's not sufficient, there's a tutorial on the LWJGL wiki here which is about fonts using Slick-Util. In the tutorial TrueTypeFont is used, but UnicodeFont should work the same way.