Re: 2004 Taurus serpentine/water pump belt?
The tool you're referring to is aptly called a "Serpentine Belt puller". It's basically a thin bar and half height sockets. I bought a kit from the local auto parts store. It came with 2 different bars, 3 metric sockets and 3 crows feet.
As I recall the kit cost about $20. Well worth case as I've changed about 5 serpentine belts with it, and can change a belt in less time than driving to the garage.