With no offense to anyone, I have never find the need to change from the default setting in OpenAM via the Administration Console.
In most production environment, there is usually a dedicated filesystem partition for logging purpose. Our practice has always been to create a symbolic link from the default log directory to the dedicated filesystem partition - be it on Unix or Windows.
Nothing too difficult and easy to achieve. Why spend so much time trying to re-configure?
Different school of thought, maybe.