What you need:
-trackpad (I used a Synaptics TM41PUZ307)
-male PS/2 connector with cable (or a 9-pin serial)
Step 1: Remove Trackpad From Laptop
Step 2: Salvage a PS/2 Cable
Step 3: Cofirm Pinout of PS/2 Cable
Your wire colors may differ, mine where as follows:
pin1 = DATA = Red
pin3 = GND = Grey
pin4 = +5V = Brown
pin5 = CLK = Yellow
Or, you can wire to a 9-pin Serial port old school mouse style. This is also nice idea to use on a desktop as a secondary mouse.
pin4 = DATA
pin5 = GND
pin7 = CLK
pin8 = +5V
*You could even wire to an AT keyboard.
Step 4: Find Pinout for Trackpad.
Synaptics has a great resource for helping you determine the pinouts of many of their models HERE.
My Synaptics TM41PUZ307 wasn't on the list, but an internet search turned up this:
pin5/6 = GND
pin7/8 = CLK
pin9/10 = DATA
pin11/12 = +5V
Step 5: Solder
Step 6: Mount
If you wish to use with USB, you must purchase a "PS/2 to USB Keyboard and Mouse Converter."