If I understand your posting correcly, what you want to do is labor intensive. What you might try is taking a wet sponge and soaking the spackle. Once it's a bit damp, take a drywall knife (something stiff, like a 3-incher) and try scraping the spackle off. If this doesn't work, just slap some 1/4 or 3/8 inch wall board over the old walls, tape and finish them. That will give you a great surface to paint with a lot less work. Good luck.