Looks like it was me misunderstanding the dopey dialect of I2C this chip I'm talking to was using.

The question I really wanted to know was how I could tell the atmel 8052 to either a) move pins simultaneously or b) to move with a delay

Turns out that the other chip was forcing the line when I didn't think it should have been (it was under the impression I wanted to read)

And sadly, you must be thinking of the wrong I2C protocol, I'm fairly sure this one doesn't have a reset available - two wires .
It crashes with the dataline held low for all eternity.

Anyway, thanks for the suggestions. Glad it turned out not to be me managing to drive two pins simultaneously. (Though is it possible to do that if I wanted to? For some other application, I mean)