1080p output with 1920x820 custom resolution resolution, custom, output

tom

So I've just installed my new 2.35:1 PJ screen and I figured out I could basically create what seems to be a quot;fakequot; resolution using the NVidia control panel, under Resize HDTV Desktop (I say fake because my PJ still reports it as a 1080p signal). So I create a 1920x820 resolution, which fits my screen perfectly (and wow does XBMC look good using the Horizonz skin on an 11 foot wide-screen!). I was skeptical that this was actually the resolution recognized by XBMC, but I check, and sure enough it was. So I thought I was all set, but then I tried to play some 2.35:1 1080p content, and noticed that XBMC scaled it down. Now I rationed that this is being done because the screen resolution is lower than the 1920 x 1080 that the content is comprized of, and of course that makes sense, but is there any way to tell XBMC to NOT scale it? Of course then I'd also have to tell it which horizontal lines to display. It would be so great if I could utilize my whole screen for XBMC, it just looks so much better than the 16:9 alternative!

I suppose I may be able to use some video editing utility to crop the video content, but that kind of thing takes forever!