IM harassment

Here's my situation:

I use my AOL screen name for work a lot - the nature of the work I do makes it easier to communicate with supervisors, etc. in chat. The downside is that my SN gets bounced around offices a lot, and that's where my trouble comes in...

It appears that the office contact sheet got into the wrong hands, and now there is a person who is harassing me via IM. I am not in a position to reject all unknown screen names, since I often have new colleagues (woo, freelance!) who need to speak with me quickly. However, this person has twice set up new SNs to harangue me, and I'm becoming nervous that their abusive behavior will escalate.

My question is this: is there a way to ***** their IP or any other identifying information using just the screen names I have? Google, Zaba, Facebook, Myspace all have nothing on the SNs he/she/it has used.

Thanks in advance to the Net Tools community.

megf