If you ever need to work out wiring again, this web page makes it pretty darn easy:
http://www.piclist.com/techref/io/stepper/wires.asp
as to making that into a bipolar configuration, see:
http://www.piclist.com/techref/io/stepper/wires.htm and notice that the only difference between the "6 wire unipolar" and "4 wire bipolar" is that the center taps are ignored for the bipolar setup.
I take it you were asking about the bipolar only out of curiosity as you already have a unipolar driver?