It would depend on the application in the notification bar. Most applications store their notification icons in their package folders. just open up finder, go to applications, select the one you want to modify and right click+ show contents. go to resources and locate the icon. rename it as a back up, open it in GIMP and alter the color settings, save it/copypaste it to the directory. and thats it. just terminal "killall -kill Finder to restart the notification area.
if its a system icon the process is similar you just need to google its location in the filesystem.
My clock on the menu bar goes away, not visible. To get it back, I need to change the clock to analogue and then back to digital. It lasts for a couple of seconds and then the clock is gone again. Any reason why this is happening? I also tried to uninstall the theme but every time I do this I get: "Unsupported System: Installation cannot proceed, as not all requirements were met."