I'm assuming this is possible just by using an Oscillator or sufficiently fast LFO as the source to the Oscillator LEVEL in the mod matrix. It seems to work based on my ears.
It did make me a bit curious as to why the Pro 2 has both LEVEL & AM for each oscillator, but I guess this is just more flexible and probable was practical to implement due to the oscillators being digital (don't need two analog VCAs per channel in the mixer).
Anybody know the nitty-gritty?