Actually, I'm not sure those earlier posts are that far off, as far as the "outside" spacetime thing. If you plug c into the Lorentz contraction formulas, they do seem to say at c, there is zero space and zero time between any two "events" - in that frame. In a way, particles that travel at c, ARE partially "outside" space-time.
I remember asking about this in school and my teacher telling me the equations break down, it's incorrect to think that way about it, blah, blah, blah. Then 10 years later I'm watching a show on neutrinos and guess what, they said the same thing! If nuetrinos moved at c, they would NOT sense the passage of time, they would see zero time on their passage from the Sun the Earth, and therefore they could not oscillate. Since they do oscillate, clearly they have a small mass and travel at less than c.
Anyhow, viewing it from that perspective does make entanglement even more interesting to think about!
However, it would still be impossible to use them to send messages, either forward or backwards in time. Whether they were massless or had mass. You never know what you're going to get for sure with a quantum system upon measurement - you only know the probabilities of potential outcomes. This makes quite a stumbling block for sending messages.