FOUND IT!!!!!!!!!!!!!!!!!!!!!!!!

Looking at the error messages in my most recent test (using the Technet script method that Brink had suggested I try), there was something interesting:

"Invalid search path C:\OTSORTW in the LIB environment variable; cannot find the path specified"

Well, turns out C:\OTSORTW actually is a folder that is supposed to be present, and I truly have customized my LIB environment variable to contain it (among others I've also added). But obviously I had unwittingly neglected to actually create that folder on the Lenovo P70 laptop I'm working on. Pure oversight, but it has never caused any problem until now.

Apparently PowerShell utilizes the LIB environment variable.

So, I simply copied the C:\OTSORTW folder from another machine on which it existed onto this laptop, and then re-tried my original command sequence (again, running with WMF 5.1 exactly as it got installed earlier this morning).

AND SURE ENOUGH... IT NOW WORKS!! Obviously WinRM is totally irrelevant, and it's not necessary to activate it.