In about 2-3 weeks I'm getting an old AS/400 server (something 9406, probably 6xx or 8xx) to learn OS/400 from administrators point of view.
Will I need some special hardware to connect and do IPL (and probably install OS/400)?
UPDATE: I dont have access to any twinaxial console or a way to obtain it.
There are primarily 3 types of console connections on the AS/400:
Which one(s) you have will depend on the hardware configuration.
See System i Information (hardware) and IBM i Information Center (software) for more information.