Due to the limitations of the engine, there will probably never be a script that does this efficiently, so I highly doubt that you will have someone create a script for it, and "telling you how to do it" would be even more difficult.
Best advice, if you absolutely require this ability, is to use an engine other than RMXP.
EDIT:
As far as properly centering the player, look in Game_Player for the CENTER_X and CENTER_Y constants, they need altered, as well as the logic for scrolling the screen. What I wrote in my original resolution script should be pretty universal to properly handle that.