PartnerIntegration_PAM.pdf documentation lists integration information for OpenSSH and SunSSH, but not for Van Dyke SSH.
Van Dyke SSH is not a server, it is a pure ssh client. The Symantec PAM plug-in will work with any client as along as the client supports the specific OS PAM module used from the Pluggable_Authentication_Modules.zip download from VIP Manager.
Since Van Dyke SSH is a pure client, and there are too many pure client SSH products to list all in the integration guide, Symantec will not specifically list it as supported and include directions on how to configure it.