The truss rod tool is a special tool. You have to either buy one from Pedulla or I believe the tuning tool for an autoharp will also work (and a lot cheaper).
http://www.musiciansfriend.com/accessories/endust-autoharp-tuning-wrench
I think an autoharp tool should be fine. I have a tool that came with a lap harp that fits just right. Pedulla does sell the tool on the site as well.




