Thanks @flyride
Confirmed that it works on DSM 6.2.3-25423.
Important thing to note here is to Copy the provided "libsynonvme.so.1" file into /usr/lib64 directory.
And if you were using the previous solution of script "libNVMEpatch.sh" , dont forget to remove it from /usr/local/etc/rc.d folder.
After you place the file into /usr/lib64 director, the DSM UI will stop working so you have to hard restart the machine.
After reboot, the NVME cache is identified and shows up in Storage Manager.