A 4mm ignition wrench = 4mm combination wrench. I bought one for under $10. The special tool is a friction ratchet and is less versatile because if you back up the stud enough, you can't remove the ratchet due to inadequate fender clearance. The 4mm wrench is easier to use and less expensive. I think Sears even had a full set for $10.
You do nothing with the plastic "nuts." You adjust the METAL stud with the hex head (the thing with threads that is surrounded by the plastic nut). The top stud is for vertical aim, the bottom stud is for horizontal aim. Touch only the top stud for adjusting the height of the beam. At this point, I recommend going to the dealer. You may need to buy a new headlamp as well.
These aren't the droids you're looking for!