There are a few ways in which I have used low resolution still images (and videos) on the dome. One way was detailed in an earlier post. Another way was to use a starfield image as a background in a fisheye dome-master, move the small rectangular image to the bottom of the fisheye so that it suffers least distortion on the dome, move the anchor point to the centre of the background image, and rotate the rectangular image so that it appears at a different place on the dome rather than front centre. To move the anchor point, the tool is the "Pan behind" tool, which looks like a circle.
Another technique was to exploit the fact that after mirror warping, the bottom centre 640x480 pixels can be used almost un-distorted. So, using a warped 1920x1080 starfield as background, animating stills (or videos) across the bottom, fading them in and out within the 640 pixel boundary. For doing this with a large number of images, copy-pasting attributes like position and opacity is useful. Just move the time marker to the first of the keyframes, click on Position, Ctrl-C to copy, click on Position on the layer where you want to paste, and Ctrl-V.