I've tried to solve this one my self and for me, I still like H.G. Wells' original idea the best.
Stephen Baxter used it in "The Time Ships" which is an EXCELLENT and recent novel on the subject.
The reason I like this is that it sidesteps the issue of the actual technology involved for several good reasons, to me anyway. (Wells and Baxter simply postulate a rather quaint victorian looking contraption with bells and whistles that transports the operator as a lever is pulled. They never really explain HOW it works.)
Being and avid SF fan (and currently writing an SF novel of my own), an author knows today's readers are sophisticated and will chide any fantasy author who delves into technology that can be easily DIS-proven. Larry Niven found this out after the first "Ringworld" when Astronomy and Physics students pointed out to him how the Ringworld would ultametly be unstable, get out of kilter and eventually collide with its central star. He had to solve this in subsequent novels by adding Bussard Ramjets to the rim to maintain its stability of orbit.
So... for me, I'll delve into only the most speculative and un-falsifiable of hypotheses when it comes to constructing scenarios that push the limit. Other than that, it seems best to actually duck the issue, or risk getting your head chopped off. Wells' and Baxter's books are more about what one encounters as a result of time travel, not the technology itself of how it might work. Their little rickety devices solve the hypothesis rather nicely I think, and keep them out of trouble with Quantum Theorists.