Welcome to the Apple Support Communities
If it's not supported yet, don't expect that Apple will release drivers for your MacBook in order to install Windows 8.
However, note that your Mac is compatible with Windows 8 because you can run it, but the problem is that Apple doesn't provide the drivers you need for your Mac, so performance will be poor and hardware won't work correctly
Aparently, there's a workaround to this problem in here:
And here, if you are in OS X 10.8.3:
I am not responsible for any issues that may arise from this method. Try at your own risk and good luck!