How do you create an IMS user?

I'm trying to set up to test my IMS TM/DB application in Enterprise Developer.

From what I can tell, you have to sign in to IMS, but the only valid sign in is SYSAD. How can I get it to accept any login? Or define a different user?

I'm having a hard time figuring this out in the documentation. It appears to say that you need to maintain this like you would if you were using CICS. But for what it says to do, there doesn't seem to be any way to actually do it.

Can someone point me in the right direction?

Note: I''ve tried changing the IMS system's security to allow for unidentified users. That had no effect.