What would be the acceptable procedure (if any) for creating a Google Scholar page for someone else?
The pages for Feynman, Einstein, and others (probably including Freud) were set up manually by the team behind Google Scholar back before the service launched in 2011, as evidenced by this blog post. Without their access, I believe you need to provide an (possibly fake) email address, as done for Theodore Dru Alison Cockerell, see this question. I would, however, suggest you not to attempt creating a profile for any living person besides yourself (including Karplus) without their consent. Them not having a profile could, after all, be an active choice.