Go to the hardware store and get one of those "metal marking pens" in white. The paint is really hard and about as indelible as you'll find. Use a q-tip and clan the dot recesses on the sight with solvent.
Shake the pen up like a can of spray paint, and dab the felt tip on a piece of plastic until the paint comes out- does it look thick? If not keep shaking.
Using a toothpick, dip into the blob of paint and drop the blob into the dot recesses of the sight- make usre you put in enough that it fills the recess, but no so much it goes outside the borders.
Let it cure for 24 hours, as this type of paint seems to dry slowly.
You might also give the all-black sights a try- I found them to work quite a bit better than three-dot sights.
