Dimensions should be 256 (height) by 128 (width) pixels. Give the VRAM viewer tutorial in my previous post a try, since that's the easiest way of getting these at the moment, if all you want is a couple of specific backgrounds.
I have yet figure out the exact scheme by which the raw palette data (it's actually a Color Lookup Table methinks) works with the raw image data. I believe the images are CLUT-less .TIM files and that each pixel points backward into the "disembodied" CLUT that sits atop the images as stored in the game image. What I'm not sure about at the moment is, given that the "1pal" files are of varying size, if I just smushed all the files back together in the same way they are stored in the game image, whether they would turn out properly in TileMolester if I just specify different starting addresses for the palette. Argh, that probably didn't make a lick of sense, but I'll let you know how it works out when I give it a go.