hey, click onto this link.
http://www.hoon.tk/tech_tips/tacho.html

the important part of the link is to locate the BLUE wire within your engine bay. This blue wire contains the signal of how fast the engine is running. The blue wire of concern is located near your driver side engine mount. It has a rubber cap covering the plug that is attached at the end of this blue wire. the pic of the blue wire is in this link

http://www.hoon.tk/tech_tips/large_images/tach13.jpg

You have to splice into this blue wire. Once you have done this, u just got to find the wires for +, -, and dash light. these wires can be found in the wires behind the radio.

hope this helps.

cheers