Realistically, that would be nearly impossible. So unless you're planning on learning z80 assembly, you'd probably need to recruit someone to produce the code for you. If you do in fact only need downscaling in one direction, it doesn't sound like it would be a huge undertaking, as one would just need to cut out the downscaling logic for the other direction from the existing scaled sprite Axiom. Or, it could be generalized to support separate horizontal and vertical scaling factors, and you'd just use a factor of 1.0 for one of them.