Yes - it's a tailless, udderless, retextured, scaled-down cow. It looks sufficiently sheep-like from a distance. The texture is based on a highly modified version of the sheep texture from The Witcher, remapped to fit onto the NWN2 cow model.

Copy these files to your Override or campaign folder, or put them in a HAK pack and associate it with your module. Use the cow appearance and set it to 'cloth' armour appearance 2. Then scale it down - I use 0.4, 0.5, 0.45. A portrait icon is included (courtesy of Google images).

There's no soundset in the game that is even vaguely like a sheep though. The closest may be the deer soundset. Cows also lack attack or death animations - so be nice to your sheep and don't anger or kill them.

Just don't get *too* nice with them (nudge nudge, wink wink).