i do not think this tradition is well known in DR. when i was a kid we used natural painting methods: boil eggs with onion skins for yellow-orange colour and with sliced beets for reddish-purple. then scratch the pattern with a needle.
you may, however, try commercial food colouring. sold in some supermarkets, look for cake decorating section (usually side by side with ready cake mixes).
AND, you can mix with some olive oil,and pour any left over on your salad!
You can draw a design, or a name,etc., on the egg with a wax candle, BEFORE you dye them.
The color won't stick, and the design shows up in white.
It's "safer" to boil the eggs first, and make "Egg Salad" after Easter.