Here is a tutorial. It is a pretty simple process. You convert the footage to ProRes (at 50fps), then using Cinema Tools you can batch conform the footage to 25fps (takes about 5 seconds per clip).
http://philipbloom.co.uk/tutorials/how-to-turn-50p-and-60p-into-slow-motion...
Enjoy,
Aaron
Aaron R. Stewart
arstewart@gmail.com