I've followed the "One-Two Punch" (http://www.plantedtank.net/forums/showthread.php?t=203684) to get rid of hair algae on my moss with good results. I did leave the moss in with the excel for 24 hours before moving it back. After the treatment was done I put it back in with my amano shrimp to clean up any remaining dead/dying algae.
Another method I've used is a mixture of 1:10 3% hydrogen peroxide to water for 2-3 minutes and then just rinsed the moss with water afterwards. I have dipped for around 10 minutes because I wasn't paying attention, but the moss did not fair as well. The moss did still bounce back though. It may be helpful to start off with manual removal for either method.
Another method I've used is a mixture of 1:10 3% hydrogen peroxide to water for 2-3 minutes and then just rinsed the moss with water afterwards. I have dipped for around 10 minutes because I wasn't paying attention, but the moss did not fair as well. The moss did still bounce back though. It may be helpful to start off with manual removal for either method.