Step 1: Download the files above and connect your PS Vita to USB using VitaShell application or using the FTP client MolecularShell and connect to your PC.
Step 2: Navigate to the directory ux0:/VitaShell folder and copy the "Snes9xVITA.vpk" to this directory.
Step 3: This will be created automatically when you install Snes9xVITA on your Vita but if you want you can create this directory manually "ux0:/data/Snes9xVITA" your ROM's will go in this folder.
Step 4: While in MolecularShell or VitaShell on your Vita, navigate to your ux0:/VitaShell folder and select your Snes9xVITA.vpk by pressing X and then confirm the install and your done. Any Other ROM's you wish to put on your Vita refer to step 3.