"Maybe the 'Opera (Single User)' entry located in the
second post here for winapp2.ini will work." Note: I haven't installed Opera 9 Beta therefore I don't know if it will work or not.
Edit:
If it doesn't work you'll have to wait for the CCleaner developer to officially support Opera 9, however I wouldn't except it to be supported until Opera 9 is a final build version and no longer a beta version.