Setting up the 256 indexed color palette is less obvious in GIMP than in Photoshop. I know the last two slots are supposed to be the transparent colors, but what would be a simpler way of setting up the palette? The way I'm doing it now is to set the image size to 130, try to put as many colors in the image as possible, put a stray green and magenta pixel on the extra pixels, set the image to Indexed and rearrange the color ordering in the palette (and I'm assuming that the "255" is technically 256?), then crop the image back to 128. With Photoshop, one could set all the extra empty color slots manually.
Anyway, here's the pavilion textured.