You can't add points on the Nintendo website though?
AFAIK, Wii Points can only be bought by:
1) Buying a scratchcard & entering the code into the Wii Shopping Channel.
2) Buying directly from the Wii Shopping Channel using a Credit Card.
The "Nintendo VIP" codes you get with the hardware & software only give you "Stars"...which are pretty crap from what I can see & simply let you buy "amazing" things such as, e.g. ... desktop wallpaper.