I'm not sure how a mantis is different than any other shrimp but I would imagine you would set it up like any other tank. 10lbs of rock and 10lbs of sand should be good. General rule of thump is 1 lbs each per gallon.
Filtration can be different from tank to tank. Some guys say you need to have a mechanical (floss), biological (rock and sand), and a chemical (chemipure). In my tank I had floss and chemipure and my live rock but for the past week or so I've only had my floss and rock and all my perams have been nearly perfect.