Not sure if TW carries them at the moment, but I know there's two sets for the original Trisys 260 on some big auction site right now that should fit the Twin Tube (just do a search for "260 grommet"). The model/part number is TK59.
One guy is asking for $34 for it. That's too much. Do you think the grommets from a Liquidmetal Radical Oversize will fit on the Twin Tube Radical? I think most if not all of the Radical Oversize racquets are the same mould right?