As you know, the extra buttons fo the genuis ergo 520 & 525 dont work with any of the games with the given driver cd, though it works well for the windows applications and multimedia functions. The problem seems to be with the driver and the software and not with the games. The workaround i have found is to download and install to IO Centre software from www.geniusnet.com
and then using that software to set your extra keys to four keystrokes on your keyboard (i used q,w,e & r). Now when you try to bind those buttons to any game they will be recognised as their respective keystrokes on the keyboard and you will be able to use 4 extra buttons, namely the 2 thumb buttons and the 2 buttons above and below the wheel. This worked for me and maybe will for you too. I have tried this trick on UT2004.
Note: The tilt wheel and dpi button will not be recognised.