Font colors are defined in UIFILEs. I suggest you to look up the element of the nickname/status/PSM in UIFILE 923 and then check out the style UIFILE for 923. You should be able to find the style definition for the element there, and there you can add/change the color attribute.
Aah... it's great when you have skinned Messenger before!
EDIT: Weeeeee 1000th post!!!11!!1!one!11!eleven!
Shall I waist another tid on it?