I am going to assume that you have your OS on the internal disk in a default type installation on a SPARCstation. Get an external disk of same capacity as the internal OS disk. Set the target to an unused target (lets say "1"). On the workstationto copy from connect the external disk drive (glove box type enclosure) and reboot. from the root command prompt: dd if=/dev/rdsk/c0t3d2 if=/dev/rdsk/c0t1d2. On the target machine, boot off the external disk and then reverse the dd command.
Analternative, if you are networked, would require a minimal UNIX OS installation on the target machine. You can use the cpio command piped through a remote shell to clone a workstation. Either method requires you to edit pertinent system information (hostname, IP address, etc.) on the target machine, of course.
Caveat: Above suggestion is based on Solaris 2.4. I.e., "c0t3d2", I assume, addresses the default boot disk, whole disk (versus individual partitions). Also, I am assuming no volume managment.