Hi,
I would agree with the previous replies but would add also you do not mention what you will be using for your backup: native commands, tar? fbackup? make_recovery? etc...
If its native (I supoose sam uses fbackup but I havent tried...), it can be done by giving oper the rights to backup via restricted sam (sam -r, and give oper the privileges on backup/restore)...
Although for security sudo su2 etc are the best way to do things, you could until you define a sudo policy also allow oper to rlogin root by creating a .rhosts file in root directory with oper in it, which would allow oper to rlogin/connect as root without having to know the root passwd, dont forget to chmod 400 on the file...then in .profile write a check if it oper that connected, to display a home written bakckup/restore menu...
Just thoughts...
All the best
Victor