Check the website Fable - its actually quite an interesting idea that may be able to be applied to other Infinity engine games. And they are playbalancing it right now - apparently the conversion takes just a few minutes - its the balancing and bug fixes that they are working on now.
Essentially it involves importing all the scripts from BGII into the Icewind Dale 2 engine - and taking advantage of the 3e rules and stat system.
Here is a clip from the site:
Key conversion points:
- Uses IWD2's spell system (no more Time Stop, Chain Contingency, etc.). Don't worry, mages will remain difficult foes.
- All converted items are automatically given descriptions based on their actual abilities, so no matter what the BG2 designers or my converter were smoking you'll know what is going on.
- Item damage and feat requirements are taken from 3E (so warhammers do 1d8 base damage, katanas use the bastard sword feat, etc.).
- All monsters are converted to 76 + (level/3) stat-point characters. Feats are chosen (using the same rules you would use, etc.) based on classes, spell memorization tables are filled out.
- IWD2's "scaled experience" thingy is employed, so if you're 20th level you don't get XP for killing kobolds. (If you're one of the few people who prefer it the old way, it's easy enough to mod MONCRATE.2DA so that you get the same reward for killing a CR X for regardless of your level.)
- IWD2 skills like Hide, Spellcraft, Arcane Lore and Concentration work correctly. Both your characters and enemy creatures have them.
- Trap, lock, hide and lore (etc.) difficulties are converted from BG2's 1-100 scale to IWD2's 1-40(ish) scale.
- Still leaves IWD2 completely playable, if for some reason you want to

. New strings are appended to dialog.tlk, converted resources are put in their own namespace.
Cool stuff - I love BGII - but I like the 3e rules of IWD II better than the 2e rules.