Debian - allow user to be root only for specific commands
Add to your /etc/sudoers file the following line:
user ALL=(root) NOPASSWD: /bin/mount,/bin/umount
where user is your non-root user and /bin/mount,/bin/umount is the list of commands you want to execute as root.
Now the non-root user can use the sudo command to run /bin/mount and /bin/umount with root privileges.