Per E.B.:
Multiboot is easy to install using PLi based images. The method for this is simple:
(1) Make a folder named "downloaded_images" on the root of a usb drive or on the root of hdd.
(2) Move the Zipped multiboot image(s) that you want to install into the folder that was made in step one.
(2) Using the receiver's remote, Press Menu, Setup, Flash image, then press Ok.
(3) Select Downloaded Images, and again press Ok.
(4) You should see the image that you downloaded, which begins with North America. Highlight it and press Ok
(5) Select a slot number, then press Ok
This should start loading the image in the slot you selected. I would select an empty slot so you do not write over what you already have. IF you want to use slot one, make sure to entirely backup the image before you overwrite so as not to lose anything.
Follow instructions on the screen while loading the image.
To switch between images, go into the Standby/Restart menu and enter the Multiboot selection, and pick which one you want.