Let's say we want to clone disk c0t0d0 with c0t1d0 

1) prvtoc /dev/rdsk/c0t0d0s2 | fmthard -s - /dev/rdsk/c0t1d0s2
2) use newfs to create the filesystems on c0t1d0.
3) use installboot to install bootblocks on the new disk (c0t1d0).
3) create a temporary mount point, say, /clone,
4) mount the new slice (say c0t1d0s0) at /clone.
5) use*   * ufsdump 0f - / | (cd /clone; ufsrestore rf -)
6) unmount /clone.
7) repeat  steps  4, 5, 6  for the  rest of the slices of the new disk.
8)  modify the /etc/vfstab  in the new disk to use its slices.