Have you tried
http://www.local.ch/?
I have to verify addresses a lot in my voluntary job and I find it very easy to use (and I'd say 97% effective).
If you know his name and location, you should be able to find him. Either via name and post code, name and commune or name and canton. Obviously the more specific you can be the better!
The other thing you can do, if your language skills are up to it, is call the commune office where he lives and ask them. I've never done it personally, but my colleagues (at said voluntary job) have. They've had no trouble getting the information (it's a magazine - to update our subscriber's addresses), so I think if you rang up and said you needed it for a Betreibung they would help you.