I would think that steady pressure would work and be worth a shot first.
The manual's brake bleed procedure is a little vague on the combination valve during regular bleeding, probably because the valve doesn't normally come into play, but when you look at the service procedure for replacing the valve, it says that the metering rod has to be held in during bleeding.
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I'm guessing that holding this pin down prevents flow into the front lines by keeping the metering valve closed, increasing pressure and allowing the differential piston to re-center and allow fluid into the rear lines.
GM has a tool to keep the pin down--it looks like a money clip and is priced like most Kent Moore tools are--but using a c-clamp may work if you're by yourself.
Since it's supposed to be held down for bleeding, I would think that cycling the pedal would not matter so much though it may help speed up the flow of fluid into the valve and formerly isolated brake lines.
It definitely wouldn't hurt to bleed the cylinders after you get flow into the lines again. If the pin is down, though, the front lines may be closed off to pressure, so I'd allow the metering rod pin to function as normal and then bleed all four corners.