"kind of borrow" heheh
You're Wii motion plus is the same one as here :
So using the connections on the left you know what to connect to your nunchuk (the two connections marked as "3v3 Vcc" separated by the SCL should be connected together, it lets the WM+ know a nunchuck is connected).
Now the order of the connections might differ on your nunchuck. Looking at this diagram from www.multiwii.com
, if Alex is using an original nunchuck too, should help