Any of a number of commercially available backup engines for NetWare that use TSAs can be used to perform the backup. The UnixWare NLM package includes the SBACKUP.NLM software, with slightly different versions for NetWare 3.X and 4.X.
Once you load the backup engine on the server, the backup procedure is specific to the backup engine.
Refer to the NetWare documentation for SBACKUP for more complete details on its use than are provided here.