Initially I had a lot of issues getting this jailbreak to work, but after I found some more info, it now works.

At first I was getting the issue:
Unable to find gBdevList
Unable to find fs_mount
Unable to find fs_unmount
Unable to find fs_load_file

but after following these directions, it works:

1. Make sure you’re using Greenpois0n RC5_2 (RC5.2 works too)
2. Make sure device is connected to your Mac
3. Open Terminal
4. Type “cd Desktop” without quotes and hit enter
5. Type “open Greenpois0n.app/Contents/MacOS/greenpois0n” without quotes and hit enter. A second Terminal window will open and Greenpois0n will start
6. Follow the instructions in Greenpois0n to enter DFU mode and it will jailbreak

if you need a place to download greenpois0n you can go here:
downloads.gregtam.com