Okay, so...I tried didling with my zMud colours a bit, change the background to white and the text to black and all.
But after didling like 10 minutes with it, I just couldn't manage to get the actual Mudoutput to turn black. Prompt, echos, everything I know how to change...but the mudoutput just stays -grey-. Any way I can change that, or is that some sort of perma-setting?

Prefrences, colors Try rightclicking on the main screen?

View -> Preferences -> Colors -> Default text.

Lusternia sends colors based on a black background, though, so you may have troubles seeing certain messages, such as text in white?

No, actually that's exactly my problem. When I change that, the only thing that changes color is my timestamp.
As I said, I tried out all of that...nothing working, normal text stays gray. >.<

change the mxp settings or something?

That's why I felt it important to note that IRE sends you the ANSI color codes, which makes the colors change regardless of your client settings. Theoretically, the "default" color code (ESC

I've had the white background since day one. I made a trigger that turns the text in white to a more readable color; everything else was able to be done using only the settings in Preferences.