I guess you can do that by using Moga VK and Moga Universal Driver app from the Play Store. Basically you use these softwares to register your Moga as a virtual keyboard. Which then can be used to map the buttons on any emulator that allows you to map customized buttons. If you're having problems you can youtube search How To Set Up Moga Controller For Emulators and just follow a video that teaches you how to map it as a virtual keyboard (there will be more than a few).