It requires root o set up a chroot jail. Not to be the user trapped in one. If it was not AIX I would suggest chroot.
A chroot jail is:
1. user is limited to the commands you provide
2. user is trapped in his/her directory.
chroot comes from the fact that the root directory for a normal user is the / directory. chrrot manes to change the root directory, such that
/home/joe becomes joe's / directory. He can only go down that directory tree to subdirectories.
The reason I am not taking a solid position is that AIX has some 'interesting' features that other UNIX flavors do not have. So for all I know that post I cited is correct. For solaris, for Linux, and for HPUX the answer is chroot jail. Since none of the AIX guys havde answered:
This is for a login account to a chroot jail using openssh.
The Best Linux Tutorials: Openssh with AIX chroot