You'll need a blocker to keep the poly from bleeding through. If you're not sure what to use, visit your local Paint Retailer. (They're in the Yellow Pages under 'Paint - Retail'.)
I believe you need an oil-based primer for painting over poly. Kilz is good stuff but unless you're using the latex based product, I wouldn't use it unless you can open a lot of doors and windows. The smell will hang around for a few days! (Again, I don't think you can use a latex primer.)
Do sand the surface so it's smooth. Then use an old bristle brush to brush out the residue from any corners on the cabinets. My best to ya and hope this helps.