I build 3 phase drivers with the HA13532 controller from Hitachi and the SLA6023 driver. But both saved from dismantled kopiers.
stragenmitsuko programmed a sequencer for a 3 phase star motor in two 16V8 GAL's and I put them before the SLA6023 and that is working well as long as you do not need microstepping. Only full and halfstep can be done but with my motors halfstep is 1200 steps/revolution and I am running my router with the HA13532 controllers in halfsetp too.
Look at http://www.cnczone.com/forums/showthread.php?t=39222 (Designing a 3ph stepper driver) for the thread stagenmtsuko started about designing a 3 phase stepper driver.
In stead of the SLA6023 driver a set of bipolar darlington transistors can be used of course.
I am now building a more or less universal driver with three SLA4391 drivers I have. I will have 3 full bridges and 6 halfbridges then to test with 3 phase star or delta, 3 phase bipolar and 5 phase configurations. I tried to use mosfet drivers, but that stranded at the complexity of driving the high side mosfets.
If the bipolar drivers are running well I will start again with mosfet driverstages.