It would need to be able to both save and load, tricky stuff.
Another approach is to run the NWN game files using another Gold Box game, like Treasures of the Savage Frontier. This assumes that the games have the same sort of Ecl functions, which I don't know if it is true.
If it worked you might need to rewrite the Ecl files to reflect the fact that TSF has one Ecl file while NWN has three or more.
There may be other complications like different offset numbering systems.