If you can, buy a kitten feeding bottle. They aren't very expensive and he will be able to latch on and suckle.
From the Kitten Rescue web site:
If you are using a bottle, the size of the hole in the nipple is critical for success. If the bottle is turned upside down and formula dribbles from the nipple, the hole is too large. Use of this nipple may cause choking and formula ending up in your kitten's lungs. If the bottle is turned upside down and formula comes out only after considerable squeezing of the bottle, the hole is too small. Use of this nipple will result in your kitten becoming discouraged and refusing to nurse. The hole is the proper size if the bottle is turned upside down and formula drips slowly from the nipple.
The nipples supplied with a nurser bottle or kits are not pierced. To pierce the nipple, wet it thoroughly inside and out with the boiled, cooled water and then heat a small pin or needle in a flame until it glows red. Quickly pierce the top of the nipple and remove the pin. Test the flow of the bottle and repeat the process if the hole is too small. Rinse the nipple thoroughly with more boiled cooled water, making sure to squeeze some water through the hole.