If it's not listed, it's not supported. You can enter it as an enhancement request here on the forums, or talk to your IBM Rep to request it through the official channels.
However, 'unsupported' doesn't mean 'won't work'. If the APIs are identical to AWS S3 APIs, then CMOD should be able to store and retrieve data from it. More advanced functions (WORM, etc.) may not be compatible.
If you do go down this path, you'll need to test it extensively.
-JD.