It appears I already have the Gradient 2 node in 2.22, but perhaps you're adding more to it?
No - the version put through yesterday in the TEST version is the version I was referring it. There is probably an option for a Gradient 3 node too, which allows up to 10 control points (pins that a texture or rgb color could be plugged into) and 10 position floats. But not sure of people would use it or not.
I think the trouble I'm having in this particular scenario is coming from possibly two things: even when using MODO's "stepped" slope, there's still a slight transition between the colors, and also there's no way to clamp Octane's random color float value output. If it could be clamped to two decimal places, that would translate to whole percentages in the gradient input and would skip over transition areas. Either that or something else completely different is going on, like Octane isn't receiving MODO's input slope type properly.
The Octane gradient node is LINEAR - and the Gradient 2 node samples it every 10 percent (rather than extracted the actual control points from the Modo gradient control). So I don't think it will do exactly what you are trying to achieve.
On-line manual reference:
http://render.otoy.com/manuals/Modo/?page_id=1106Paul