I read that Ethereum uses Ethash as proof of work algorithm. But since there are other PoWs like NeoScrypt (used by Phoenixcoin), scryptJane (used by LEOcoin).
Is it possible to use the above mentioned algorithms as PoWs.(Obviously it could be done but the gist of the question is how much effort (changes in source code) is required to do so). Does changes in only file replacing the algorithm will do or would it be herculean task.