To do as you wish, you could use chroot in the /etc/password file in the last field (where the shell is). For example, to make the user have a root of /home/misha, then you would change the final field in /etc/password to be something like:
/usr/bin/chroot /usr/misha /bin/sh
In most implementations (and the GNU version) the shell does not have do be specified because without an argument the default shell is the command.
As PxT suggests, chroot is the approach. However, building a chroot environment can be tricky because commands that a user would normally have access to are not available unless explicitly under the new chroot directory. In other words, you must build a new environment under the new pseudo root file system and provide all commands.
This could be difficult for newbies, but it can be done I suggest reading the chroot manpage and supporting documents carefully.