I haven't actually had to do this but here's what i would do. Get the lights where they are just loose enough to move by hand. Put the bike on a level section of street after dark. Sit on the bike and move the lights until you get them into a good position. You may need some help if you can't reach the lights while sitting on the bike. Don't forget to tighten them down after adjustment. I've never adjusted the lights on my Heritage but they look pretty much in line with the headlight.
Current bikes in the stable:
2009 Street Glide
- 107ci, stage III heads, D&D Fatcat exhaust, Andrews 54 cam, TTS, 108hp 122tq
2003 Heritage Softail Classic
- 95ci, stage III heads, RB LSR exhaust, S&S 510 cams, 100hp 102tq