Installing Tach on 99

Anyone have any pointers on installing a tachometer to a 99? Especially with the wiring of it? I just bought my Prizm and desperately want a tachometer so I can gauge for fuel mileage.

Thanks!

If you buy one make sure it has instructions with it. Normally they are wired to the terminal that pulses the coil to fire the plug. You need a wiring diagram http://www.alldata.com/ has good diagrams. Cost appx.$29.95 per year. If you have a Haynes manual look.