You can get texture filtering already.

What you are asking for is texture scaling filters..
Totally different things.

The textures are filtered with AF as it is. They just just super low res, even after the upgrades for the Mobile/PC version from the DS ver.


If someone can extract all of the textures from the game, you can use Waifu 2x or the ImageResizer from this
https://code.google.com/p/2dimagefilter/
Which has a TON of different available scaling/filtering methods to use.

Or look for someone to develop a method like used in PPSSPP or here http://blog.metaclassofnil.com/?p=763 to custom scale the textures in real time.

No switch in driver software to enable texture filtering is going to do what you want.