Gulenko goes into it fairly in-depth here, along with a bunch of other stuff: The Structure and the Elements of the Socionics Model - Wikisocion

Gulenko describes the Time dimension a little differently: he describes it as meaning that a 4-dimensional function effectively has no time restraints on it, while a 3-dimensional function can only be used for shorter periods of time.

So for an LII:
Ti is 4-dimensional, meaning that we can logically analyze pretty much any thing, any time, any place.
Ne is 3-dimensional, meaning we can consider the abstract properties of objects in any situation, but only for shorter periods of time.
Fi is 2-dimensional, meaning we can't grasp well the subtleties of interpersonal relationships, so we have to rely on what we see other people doing as our "script" so we can play the "role" of someone strong in Fi.
Se is 1-dimensional, meaning that we can't even figure out a "script" based on the actions of others for using Se, we only know what has worked in the past.

It's much the same for the vital ring, only we don't consciously think about it in the same way.