auto mount SMB share on Solaris 10

I CANNOT use autmounter so should I just write the command as an /etc/rc script or is it possible to auto mount the share via the vfstab?

Have you read How to Add an Automounter Entry for a CIFS Share (Solaris CIFS Administration Guide)?

I have but I cannot use automounter due to security reasons (not my call).

Yeah, I know this isn't helpful, but what a dorked-up, brain dead decision.

Whether you can access a file system or not doesn't matter if you do it with automount or manually.

Whoever made that decision doesn't know what he's doing.

I believe it's a remnant of Windows based procedures; you know the whole "flash drives" thing.