This may be unnecessary but:
1) you will most likely need a leaf shutter lens, unless your focal plane shutter synchs at a very high speed;
2) if you use the flash on "auto", be sure that the sensor is pointing toward the subject.
I've done this a lot with colour negative film (Portra 160 and before, Vericolour III) and using the "one stop" adjustment, on manual, works well.
Also remember that if you are working in crowded areas, anything that gets between you and your subject will tend to be overexposed and to light, due to the flash (or alternately, your subject may turn out too dark).