Use the cluster control utility crsctl to add voting disks and to remove them.
crsctl add css votedisk /full_path_to_voting_disk
crsctl delete css votedisk /full_path_to_voting_disk
For backing up purposes, the voting disk is merely a chunk of binary data and as such may be copied out to a normal file system table, for backing up.
saving the voting disk data to filesystem
dd if=/full_path_to_voting_disk of=/full_path_to_filesystem_savepoint
restoring the voting disk from the filesystem
dd of=/full_path_to_filesystem_savepoint if=/full_path_to_voting_disk
