I know a few folks who broke open "empty" cartridges and saved the remnant few ml of inks in small glass jars. They use that ink to spot.
I never have issues on coated papers, but if I am using art paper, I blow it off with canned air before I print. For me, this has pretty much eliminated the white flecks after printing so I don't have anything to spot.
Try this: print sections of your image - the parts with the spots - on the back of acetate, overhead film, or any material that makes the ink bead up and not dry fast. Use a fine brush to stipple spot as you would with regular photo. You could also print CMYK ramps.