I am not sure if this method works because I have not yet installed Windows 8 on my Acer notebook with HD3200 on-board graphics. But you do not lose anything trying.
If you have already downloaded AMD CCC 12.10 driver pack for Windows 8, double-click this driver pack and unpack it to a loction of your choice. After the pack has finished unpacking, open Device Manager and find your HD3200 adapter. Then switch to Driver tab and click Update driver. When Update driver window opens, click "Scan my computer for a better driver". Show the path to the folder where the driver .inf file resides. Be sure to put a checkmark in the box "include subfolders".
Note: Most probably, HD3200 chip identification is not in the .inf file. Therefore, it will not be recognized.
EDIT: Please use the correct driver pack for your computer, x86 or x64.