Make sure your MAC is set to an Artnet address (e.g. 2.0.0.10) and the same subnet as the Grandma. You should then be able to patch your Catalyst input to whichever universes you are transmitting to. This is in the drop down menu for each input that normally defaults to "CIB" next to the DMX address for each layer.

I have done this with the GrandMA and it seemed to work fine.

I don't quite understand what you mean by "0-0" as ip addresses are usually x.x.x.x

Cheers

Toby