Two things worth taking a closer look at, though:

1) you are using the Bluetooth Setup Assistant to pair the Wiimote 
2) Remote Buddy seems to keep stalling at "Configuring device .." on 
your machine

Regarding 1): 
You shouldn’t use that assistant for your Wiimote at all. Remote 
Buddy is all you need and that you should use for that purpose, really.

Regarding 2): 
This sounds like the exact problem the kernel extension is in place 
to solve for Bluetooth devices: communication errors caused by 
elements of Apple's Bluetooth stack. Please have a look at your 
system.log via /Utilities/Console.app during pairing. Do new lines 
appear during pairing that carry HID in them? Any other messages 
related to Bluetooth or that only appear while attempting to pair? 
Any such output would be very interesting to me.

I don't know, whether 2) stems from 1) or whether your Wiimote has a 
different device address prefix than is detected by Remote Buddy's 
kernel extension. To exclude the latter: can you please have a look 
at System Preferences / Bluetooth and have a look at what "Device 
Address" is listed for your remote?

Also, is your friend's Mac a PowerPC or Intel based machine?

You may also try to do the following: 
1) Use System Preferences / Bluetooth to remove your remote control 
from the list. 
2) Reboot. 
3) Avoid Bluetooth Setup Assistant and use solely Remote Buddy to 
pair your Wiimote.

Best regards, 
Felix