You're correct Sandrie, AppLocale won't work because you have to go through OGP's launcher.... But, it might work with the VLOW shortcut that you create using the method in this thread:
How to enable VLOW Post-Hell's Door Update
I haven't tried it, but there's no reason that wouldn't work, AppLocale doesn't change the executable any, just tricks it into thinking it's running in a different system locale from default.
But, your research into changing system locale says that trying this is probably pointless as it's unlikely to change the font size any.