There are no validated Matrox drivers for Windows 8. Some users on the Matrox forums have used the Windows 7 driver and claim to have no problems using the MXO2 with Windows 8, but other have reported issues. You would be best advised to take your query to the Matrox forums.
There is Windows 8 beta support using the 126.96.36.1994 driver for MXO2 on PC
Safe Harbor Computers