(1) Make a folder named "downloaded_images" (no quotes, but you need the underscore!) on the root of a usb pendrive or on the root of your hdd you have connected to record shows.
(2) Move the Zipped multiboot image that you want to install into the folder that was made in step one. (tnap-3.2-osmio4k_multiboot_ofgwrite.zip in this case, do NOT unzip it!)
(2) Using the receiver's remote, Press Menu, Setup, Flash image, then press Ok.
(3) Select the downloaded_images folder, and again press Ok.
(4) You should see the image that you downloaded. Highlight it and press Ok
(5) Select a slot number, then press Ok to install it.
Personally, I installed mine in Slot 2, and restored my user settings to it. It went real smooth, and afterwards I went through all the menus and made sure everything was set right. I had to make a few tweaks here and there, but it all went perfectly!