Where do you find a gate agent?
 

I would like to meet my mom on her way to another airport for a few hours in Atlanta. Where would I find a gate agent to try and get a pass to go through security and take her at her next gate?

You'll have to ask at a check in counter as you can't get thru security without a pass or a ticket. You could tell them she needs extra assistance and you need to be there to help. There's always the option of buying a fully refundable ticket if you can't get a pass, but it may take a while for the refund to show up on your credit card. What airline is she flying? The Air Tran
agents at the counter near the MARTA entrance have always been very helpful when I'm dropping off a 95 yr. old who needs whelchair assistance.