If your 3in1 is the newest kind, I don't think those work with the Opera Browser yet.
Otherwise, all you need is the correct patch for the opera browser. There are different patches for different Slot 2 carts, so you need the one for EZ 3-in-1.
Not sure where to find it, download center has the patches for M3/G6/Supercard Slot-2's and EZ4 deluxe, but not EZ3-in-1.