I just talked directly with IRS two week ago. I just mailed paperwork (form 433-D) to them to allow auto payments on my existing installment agreement that I have been paying on for about a year now. They told me that after 3 auto payments have successfully gone through that I can send in some more paperwork (form 12277) to request the removal of the lien. For more information you can talk to them directly at 800-829-0922.