You cannot do it directly from the SSH CLI interface, but you can use the Northbound Portal Interface.
To enable the Northbound Portal Interface, go into /configure/sytem/Network Management/Northbound Portal interface.
You can then use the curl command from Linux or MacOS shell in order to generate DPSKs. Below is a sample of such command.
curl -k -d "ruckus1231.0" https://192.168.120.240/admin/_portalintf.jsp