Bleeding ABS Master Cylinder

I have a '92 Buick Regal with a Delco ABS VI system.

I need to bleed the master brake cylinder. I have a bleeder kit with two hoses.

The master cylinder is bolted to the hydraulic modulator as a unit. the hydraulic modulator has four hoses from the four wheel callipers running into it. Here is the diagram:

OR

A) Do I need to disconnect the hydraulic modulator from the master cylinder, or can I just remove two lines from the modulator, bleed them, then remove the other two lined from the modulator, bleed them, and have the master cylinder done that way?

B) I have read about Gravity bleeding, where I just loosen up one bleeder screw from the calliper farthest from the master cylinder, presumably the passenger rear, remove the master cylinder cover, pour in brake fluid and wait for it to work it's way down and there are no bubbles in the line. Sounds great. Does anyone know how long it takes? I plan to jack up the front of the car slightly if I do it, to make sure everything is downhill. Should I have the car running?

Thank you for any help I can get.