Hooking a laptop to a NAM to program is more hassle than it's worth. That'd be different if you had a CP.
General Overview- Under f983, AA, Lines, select the lines you want aa to answer, and assign them to be answered by a table. AA, Tables- Assign greeting 1 for all selections, and your attendant's extension. Record your greeting in greeting 1. F982- Assign "answer lines" to Y, attendant available to Y, and make sure your attendant's extension is entered there.
You should be done.
If this isn't working for you, I'd definitely call a vendor. It probably won't be as expensive as you fear, and you can blame them if it doesn't work the way you want it to.