This Still works on 1.6! However, this Resource Pack will still look awkward on your world. Only use it on the Official Grinchmas Map, which you can download below.

This here is the original Grinchmas pack by rsmalec, but with new features that will fix any error textures that you will get in 1.2.4 and above. I take no ownership over the original pack, this is simply put here for posterity. It is reccomended that you have this pack only enabled when you are playing the Grinchmas Map, because there are some textures that will look strange if you have them enabled in your own world.

Get the Grinchmas map here:
http://www.minecraftforum.net/topic/765309-grinchmas/