Fusion drive in Sierra ?

Any pointers to instructions on how to create a Fusion drive in Sierra - using a new internal SSD and existing HD ?

Have tried various links / instructions - without success. My HardDrive already shows up as Apple Core Storage - not sure if this is relevant. Diskutil list shows the state of play before I try to create a Fusion drive:

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *240.1 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_HFS RHCSSD250 239.7 GB disk0s2

/dev/disk1 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *750.2 GB disk1

1: EFI EFI 209.7 MB disk1s1

2: Apple_CoreStorage RHCMBPro750 749.3 GB disk1s2

3: Apple_Boot Recovery HD 650.0 MB disk1s3

/dev/disk2 (internal, virtual):

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS RHCMBPro750 +748.9 GB disk2

Logical Volume on disk1s2

9C2E9CD9-1D05-4B7C-A76C-41C7C9F21CC7

Unencrypted