Remove the cabinet hardware and doors, using a screwdriver. Lay the doors on newspapers.
Put painter's tape around the cabinets to protect the walls.
Sand the surface of the cabinets by hand, using fine sandpaper. Sand lightly, to buff and degloss the surface.
If the surface is painted, the sanding shouldn't remove the paint, but merely dull the shine. Wipe off all the dust.
Brush on glaze with a paintbrush, starting at the top of each piece and working downward. Lay it on thickly, getting it fully inside the crevices and corners of the pieces.
Allow the glaze to set for two or three minutes.
Wipe the glaze away from the flat surfaces with dry rags. Wipe lightly, taking up just glaze the comes off easily from the flat surfaces while leaving it in the corners and lines of the pieces.
The result should be an uneven finish with glaze coating the small, tight areas and the original color of the piece showing through on the flat spans. Let the glaze set overnight.
Spray polyurethane over the cabinets in three to four light, even coats. Between coats, let the polyurethane dry for two or three hours, sand it lightly by hand, wipe off the dust, and apply the next coat.
Don't sand the final coat. Let it set for two days before reassembling the cabinets.