Mac OS Sierra was released yesterday. However, our good old MacbookPro 5,5 (Mid 2009) isn’t officially supported anymore. Luckily, there are people who figure out what is necessary to patch the official installation so that it can be installed again 
I’ve backuped the Macbook and gave the given instructions a try. Instead of reinstalling everything I only updated from El Capitan to Sierra. After the first restart, the Macbook shut down, as it didn’t found a valid boot partition.
So I rebooted again to the patched installation media and ran the proposed „macOS Post Install…“. I’ve selected my type of Macbook and let it patch. Additionally I’ve ran the „Force Cache Rebuild“ command and rebooted.
The Macbook booted to Sierra 
However, the FaceTime camera wasn’t detected and I wasn’t able to get it working again. Since there was a „Legacy USB Support injector“ I think this might cause the problem. The FaceTime camera is connected internally over USB so it seems to have some problems.
I don’t think this is a big problem. You’ll probably get this somehow fixed with a little time and patience. However, since I’m running a real Mac hardware (and no Hackintosh), I don’t want to fiddle around with such basic hardware problems.
Therefore I can only recommend you to leave your Macbook on El Capitan (10.11) as the largest supported OS. Seems that Apple wants to get rid of devices older than 7 years, even if they are still doing great (with a SSD and 8GB RAM).