Well, if you don't want to breed Snorlax, then there is unfortunately no way to find a Munchlax in the wild, except the PokeTransfer.
If you don't want, or you don't have the PokeTransfer then the only way to get your favoured Munchlax is to breed with your Snorlax holding a Full Incense. Sorry.
Hope I helped. :)