I mentioned in the post that it's on the beta exe from a specific beta version. Ie. NOT 1.54!
So...
X:\Program Files\Bohemia Interactive\Arma 2\Expansion\Beta\arma2oa.exe
After beta 74123 is installed. (I think it was that version, check my other post.)
Edit: I'll show screenshots to show it later if I'm not lazy.