How do you replace this kind of roller housing?
Hi there! You're correct. Mirror closet door guides like the 23-093 (among many others) typically attach to the door by hooking directly into slots in the frame. No additional piece is necessary.
Removal can be tricky, since once they hook in they are held pretty solidly in place. You'll have to take the doors down and place them on a stable surface, then use a pair of needle-nose pliers to grip the old housing and firmly work it out. There's no trick to it beyond that, short of using a little elbow grease, so keep at it and eventually the hooks will come loose and you can safely remove the guide for replacement.
Please let us know if you had any other questions!