Well I don't know about legality issues but I'll give you a how-to on painting the tails. I tinted my stock tails to a smoke color for a while too (removed later).

1. Go to your local hobby store and pick up Testors brand window tint spray, costs are $4-6 usually. Nightshades are like $20 where I live. Also pick up Testors clear coat spray while you're there.

2. Tape off area of tailights you want painted with painters tape found at a hardware store.

3. Clean area with rubbing alcohol and let it dry.

4. Spray window tint spray on with smooth even strokes and light coats. Apply about 3-5 coats when you're done. Don't make them too dark.

5. Apply about 3-5 coats of clear coat as well.

6. Remove tape and voila! You're done.