This site describes how to find your wiimote's bluetooth (MAC) address using a popular 3rd party bluetooth stack in Microsoft Windows called BlueSoleil by IVT. This section shows how to do it in the BlueSoleil's Classic View. If you are using the standard view, you should see this site.

 

Go to the BlueSoleil's main window
Go to the BlueSoleil's main window. Right-click on the orb and select Search Devices. Put your wiimote into discovery mode.

 

Wiimote is detected
The wiimote is detected and for a couple of seconds, its MAC address is shown instead of the name. If you are quick enough, you can copy the address from here.

 

Right Click Properties
If you weren't quick enough, then right-click on the controller icon and select Properties.

 

Mac address visible
The wiimote's MAC address is visible as Device Address.

 

Remove wiimote afterwards.
Don't forget to remove the wiimote at the end so the computer won't interfere.