Do you have a dog? We found a kitten that was only about 3-4 weeks old and she couldn't clean herself so I held her out to the dogs a couple of times a day and they cleaned all the crap off her (*gag* - but better than me doing it!).

You can buy kitten milk at the shop. If it is walking it is probably alright to go straight onto a fortified milk. For food - weet-bix in milk, then cat biscuits in milk and raw mince or canned kitten food.
i thought you were going to say feed it to the dog