The new "stock" cabinets that I bought and added to the existing cabinets are the same types of deals as what you're talking about.
With regards to sanding, use 100 grit on a pad sander and go over the surfaces quickly to rough things up. You're not trying to get the finish off here- just trying to scuff them up. And you don't want to do it so much that you go through the material that looks like wood. Just try to hit all the surfaces, and use a tack cloth to get rid of any dust. Spray everything outside if it's possible. If not, mask countertops, appliances, and the floors and make sure you have a whole lot of windows open. I don't recommend the second, but there's not a lot else you can do if you don't want to physically take the cabinets down and you're still determined to paint.