how do I arrange a wheelchair for infirm passenger transport from TSA to the flight loading gate?

Call or go on your airlines app. And request a wheel chair and when you get to the airport go to the wheel chair area for your airline to show them the boarding pass and they will call for an employee to take the wheel chair person through TSA with you and then they will take you to the loading gate.

When you check in at your airlines desk they can arrange to provide a wheelchair at the TSA exit.