Getting and Changing a prefab's texture?

I'm working on a plugin that creates a high quality metal ore node, meaning it only gives high qual. Issue is I have to choose from one of the three rocks to indicate that it's an HQM rock.

I know you can't use a custom texture, but even if I could say set it to a barrel's texture, that would make it more clear what it is.

I've looked a bit through GameObject and looked in the dll's to see if I could find something, but I didn't see any mention of a texture. Is this possible? If not, can anyone think of any workarounds to this problem?

The only thing client receives to decide, which object to display - is prefab id, so u can only choose from existing prefabs.