I think you'll have to go with the Predator or have someone burn you a custom tune. You can tell them what gears you're running before they burn the chip. I think the recalibrator only works with manuals. Don't even think about buying the plastic recalibration gear. They don't last long.
The Predator would run you about $400, but it can do alot more than just adjust your speedo. It's recommended by alot of people on here if you're planning on doing alot of modding.
As for the custom chip, I've never had it done so I'm not sure what they'd charge you for it. I think some tuning places can just burn you one for the gears, but I'm not certain. Maybe someone else could answer that.