There are two methods I use for fusing laser copy toner (granted, I'm not using it specifically for copper plate, I'm using it on aluminum, transparency materials, Yupo-type materials, and paper:
1. Heat. Since that's how the printer fuses it, that method always works. A heating tray will work (though, again, I've not used it this way — I actually use a heatgun VERY CAREFULLY).
2. Solvent fusing — the best one I've found for solvent fusing is mineral spirits. It doesn't really take much and it's pretty quick. Lithograph folks have been using it for some time now — here's a great video overview of how it can be used.
I HAVE removed it on metal (aluminum), using Brasso, having first softened it with the mineral spirits.