Well... I have never started the ut2k4 editor, but if it's remotely the same as in U1, you can use it to make simple adjustments.
Start the ed, find the place where you can browse classes.
Now somewhere there should be a button or menu that allows you to load classes or u files. Load the package you want to modify, and the classes it contains should appear in the class tree somewhere - unless loading the package failed which the editor log will tell you.
Now... double clicking on the class should open a text-editor-like window that lets you edit code... hopefully you KNOW what you're doing because if you aren't, you will just mess things up :-O
Do you changes, hit F7 (at least in U1 that's the key to press) to have the code be recompiled (only the currently OPEN class will be recomiled by this action). Then you need to find the button or menu that allows you to SAVE code packages and you select your package to save....
Well that's about how it works in U1, I hope you can find the equivalents in the ut2k4 editor, because I can't bother to explain to you code exporting, folder setup and recompiling using notepad and the dos-prompt
