i think it not problem to adopt gpu miner for maxcoin
https://github.com/smolen/cgminer with little changes will be work with maxcoin i think))
or can change metiscoin gpuminer https://github.com/girino/xptMiner remove shavite and metis hash and add support for getwork from https://github.com/hg5fm/jhPrimeminer/commit/cc08333c374c96d7f6b0a3e0001d4352c9d25cec ....