Conversion Process From Single-Ended to a Differential Filter
Basically, just draw a line across all of the grounds and then mirror the entire circuit over the line.  See: http://www.ti.com/lit/an/slwa053b/slwa053b.pdf

After that, you can remove the ground connections and combine series components (two caps in series become one of 1/2 the value, two inductors in series combine to one 2x the value, etc.)

You should end up with your line of inductors duplicated at the bottom with the same values, interconnected by series LC circuits with 1/2C and 2L.