Leeds manager Simon Grayson said: "Hogan is quick and direct and can play on either side.
"We have a busy time coming up and he gives us options and competition for places."
Ephraim, who joined Rangers from West Ham for £800,000 in January 2008, was sidelined throughout October with an ankle injury and is hoping to boost his match fitness at Elland Road.
The winger, a product of West Ham's academy, made only one senior appearance for the Hammers before joining Colchester on loan. He then spent three months on loan at Loftus Road at the end of 2007 before making the move permanent.