Can nsDialogs replace MessageBox?

I am having difficulty with the nsDialogs plugin documentation. I can't tell if I should be able to use it to do an informational popup message, rather than simply calling MessageBox. If nsDialogs works only to replace the main dialog, I'm wasting my time trying to get it set up. If it IS possible to do a popup, could someone please point me to some example code?
I'm using NSIS version 2.46 on Windows 7.
Slightly OT:
The reason I need to do this is because I'm using a "NSISVCLStyles" skin (RubyGraphite) to change the look of my installer. It works great for the main dialogs but the message box text comes up with black text on dark gray. It's almost unreadable. Attempting to set the text and/or background color doesn't work. It's my understanding (from a fair bit of online searching) that the skin overrides any specific text color assignments.

Then NSISVCLStyles plugin should be fixed, report it as a bug in its forum thread or contact the developer.

nsDialogs was only designed to be hosted in the main dialog but you can try http://nsis.sourceforge.net/DlgHost_plug-in but keep in mind that you cannot nest nsDialogs pages...

Thanks, Anders. I suspected that was the case, but I didn't see anything that specifically said I couldn't nest them.
I will contact the styles plugin developer.