What is the procedure for dropping off a person for departure that needs help getting into the terminal?

Ask skycap they will assist you

You can arrange for a wheelchair. I would park and walk them in. Arrive a little early. If you are not a ticket passenger you cannot go through the security check point.

There should be plenty of skycap personnel in the departure area. You can flag one of them down or ask security to direct you to an information kiosk where they will be able to request assistance to help the passenger get to the correct area.