If you have installed Vix, to install for example ATV, go to menu/Setup/Vix/Image manager select the ATV zip file which you should have put in your backup image directory and then press the blue Flash button. After another button press you will then be asked to select where you want the image put. The box will load the image and boot it. In Vix you can boot another image by selecting Menu/Standby and Restart/Multiboot and then choosing then image you want to boot. ATV and PLI are very much the same.