So, building off this thread ->
http://ecomodder.com/forum/showthrea...ons-18045.html
I have gone ahead and purchased all of the required components.
I also purchased a used alternator for a 4.7L Dodge engine, and took out the rectifier assembly. I was somewhat surprised to discover that the alternator apparently has two complete sets of Y windings. I verified this by taking a multimeter to the winding leads, and by examining the rectifier assembly. The rectifier assembly has a total of 12 diodes, and one of the common planes is split electrically. To me, that says "two sets of Y windings."
The MOSFETs are probably overkill, as they are rated for 260 amps apiece. However, they have an on-resistance of 0.00195 ohms, and calculations show an 84% drop in dissipated power, compared to a standard silicon rectifier diode.