Student Loan Garnishment - Post Judgment

A judgment for a student loan was entered against me 10 years ago. I
thought I began paying it back several years ago but it turned out I
was only paying the state portion and not the federal portion. I was
served with a Post-Judgment Garnishment order (as was my employer) 
for the federal portion (15K).

Understanding that this is from neglect on my part, I would like to
pay this off immediatly by taking out a line of credit. I do not want
it garnished from my check and I would like to put it behind me.

My question is: is it possible to settle for an amount less than the
amount owed if I settle in one payment? Should I have a lawyer handle
this for me (whether or not the amount can be reduced) and what would
I expect to pay a lawyer in the metro New York Region? Will this
post-judgment order appear on my credit report?

Find out who has the loan and make the offer.