More recent Bitcoin Core switched from Berkeley DB 4.8 to SQLite as wallet.dat database, so simple tweak won't do the job.
Forgot about that, so a fine a major rewrite will do that job :-)
Goes back to the point that I make about a lot of things here, just because you can does not mean you should. Add to that just because it's possible does not mean you can.
And in the end it's probably pointless.
Plus, this already got more and better answers than deserved.
You replied while I was posting, but this topic at least a very very very little bit did being up a valid point about version compatibility.
-Dave