I didn't edit the 2D backgrounds though, I don't really know exactly what I need to change with those.
It'll be an easy edit, but I'm not sure it will come out 100% perfectly since 945 is an odd hieght.
First start with my 1680x1050 files. The backgrounds are all the TGA files. Open them up and they'll be 1024x512 in size (textures sizes need to be powers of 2). They're get scaled to screen resolution in-game.
So to work with them, first you need to resize them to "actual" size as they appear in game. So resize them to 1680x1050 in an image editer with a good scaler algorthm (i.e. Paint won't cut it).
Then you just have to crop the appropriate amount of pixels off the top and bottom. Here's where the problem with 945 comes in - you won't be able to crop the same amount of pixels from both. It's never going to line up 100% pixel perfect with the central menu control - but at least you can get it close. Crop 52 pixels from one and 53 from another, you choice on which.
You then need to take the resultant 1680x945 image and resize it back to 1024x512. Plop that in the override directory and you're good to go.

