Well, my laptop remains in is franken-book-not-quite-working state. I've had rEFIt installed all along (I suppose I failed to make that clear in my earlier posts; I've had my 'book set up like this for so long that I take it for granted) but the 1920x1200 toshiba LCD works great in windows, and the rEFIt bootloader, and even the OS X grey-apple boot screen, but after that, it's totally useless.
vv-tim, it seems we were having similar problems. I tried using DisplayConfigX, but it wouldn't allow me to set the nitty-gritty timing junk to the settings windows used, it kept changing numbers on me forcefully. SwitchResX allowed me to, but it has seemed rather useless (i.e. it hasn't worked). Were you able to set the display timing settings (all that direct pinout stuff, front porch and sync width for vert/horz timings, etc. etc.) properly with DisplayConfigX, or was it a kind of 'close as I could' job? I'm intrigued by you success after reducing the refresh rate. I'll need to experiment more in that regard.
Regardless, it IS possible, if windows and the bootloader and even the initial boot screen of OS X can do it. Some little bugger of a gremlin in OS X is changing something it shouldn't at some point. Replacing the vendor files as posted prior seems promising, I'm going to look into that soon. I'll post my results, assuming I can get any sort of image to appear if I can duplicate vv-tim's impressive hacking feats.
The dream of absurdly high-res MBPs continues...let's make it a reality!
Also, it seems like this deserves a more centralized and accessable format than a lonely forum topic that a stumbled upon through luck on google. I've been considering rehosting this topic as an open blog (sort of like a wiki, except in a post-by-post format) so everyone can easily add their experiences and hopefully pool their knowledge into a general solutiuon. I'm sure I could get it linked to on engadget.com, hackaday.com, etc. etc. for increased traffic. Opinions?