I'm afraid I don't know what you mean by certify. My suggestion is to develop a simple, reproducable, highly-automated routine that checks key things. Run it on that server, use the app for a bit, then declare you "support" the version of SQL. That doesn't mean that everything just works - it just means that you will take support calls.
Some vendors, most likely microsoft, have a "name of OS certified" process. You could follow that.