I had a stress fracture in my third metatarsal last year. It actually broke clean and I was in a cast with crutches.
I broke my foot in the beginning of September. I was racing by mid November and back to full racing speed by the beginning of January. so it was a complete 4 month recovery to get back to 100%.
Basically I spent at least an hour a day on either a stationary bike or deep water running. I found the deep water running to be the best because I would leave the pool with my foot in better condition then when I got in. It definately hastened the rate of recovery. I took advil to reduce the swelling. I kept it elevated at least a 1/2 hour a day. When I started running again I started with only a mile at a time on soft surfaces about 6 weeks out. I was lucky that it was the third metatarsal because there was some surrounding protection b/c the break was in the center of my foot.
I got an x-ray every couple of weeks to check my progress. After the first of the year there has been no looking back.
I was reluctant to use the eliptical early on because it does place some weight on the broken bone, but I never asked a professional about it.
Hope this helped a little. Good luck.