There aren't a lot of guide out there (that I found) that show you how to do this w/o gpart. SmartOS has only basic software on it and parted wasn't one of them.

Here is how I did it:

format
fdisk
#push 3 (multiple times) to delete partitions
#push 1 to create partitions, use UNIX type
#push 2 to make none of them "active"
#push 6 to write changes

I created 2 UNIX partitions on my c1t2d0 device. My first partition is c1t2d0p1, the second is c1t2d0p2.

You can use this in ZFS like:

zpool create poolname c1t2d0p1

I don't know if UNIX partitions are the "best", but it seems to work.

I used this so I could partition my SSD as ZIL (log on first partition) and local backup (it doesn't get used very much and doesn't slow down my zil).

extra: If you want to "split" the drive instead of partition, check out this reference. It talks about p1 vs s1 vs n1 (at the end of a device).

reference: http://openindiana.org/pipermail/openindiana-discuss/2012-November/010741.html