You only have to pair once - after the EZ-Key is paired to a computer it will auto-connect from then on
First up, you'll have to make sure you have Bluetooth v2.1 or greater on your computer. Many laptops have BT built in and unless its a really old machine (< 2008), the built in BT should be OK. If you do not have BT built in, you'll need a USB dongle such as this one
99% of the time, you can just plug it in and Windows will automatically install the drivers, as there are only two main chipsets (CSR & Broadcom) and they have built in support.
The title of this step is pretty much what you have to do. Remember that you have solder the 0.1" headers to the module or at least solder wires to the Vin and Ground connections. Connect Vin to 3 to 16VDC (5V is ideal) and ground to the ground power wire.
The red LED will now blink at a steady once-a-second.
In the Control Panel, find the Add Bluetooth Device entry
If it asks you for a passcode, the pairing code is 1234