I have the Mitsu 48413. First thing I did was hook it up via s-video to do the 6-1-9 setup to set the 811 to 1080i. I then plugged the component video cables into the DTV plugs (GRB or Y/G, Pr/R, Pb/B). On the DTV port you should also have H/V but I didn't have to use those. Use the device button the remote to select DTV and hit enter. This should switch the TV over to the DTV port and you should be getting 1080i on everything as the 811 upconverts everything to 1080i.
Mark
Mark