If you don't have an old controller with SOE, officially you need an Aruba Y cable.
Personally, I couldn't afford one, so I made a 9way plug out of a shell that I attach to a Cat5e cable. I then plug in a DC PSU and do it that way.
If you'd like the pin-outs, let me know. Of course I'm non-Aruba, so if you break your AP doing the same as me, it's done at your risk of course!