There was a nunchuk eagle topic started a couple years ago but it was not answered and is now closed.
I also would like to make a nunchuk adapter in eagle. I know they are available at sparkfun.
The nunchuk adapter is basically 4 connectors. 2 on the top and 2 on the bottom.
They are .15 inches apart ( I think) and are about roughly .1 inches wide.
The top is ground and SCL and the bottom is power and SDA. I can wire the items in eagle. But I don't know how to create pads that occupy the same area but on the top is one pad and on the bottom is a different pad.
Meanwhile...2 days later....I found some helpful links including a schematic that has 2 nunchuk breakouts:https://sites.google.com/site/buildagadget/nunchuk_usb/hw_elec_nunchuk/nunchuckUSB-v13.schhttps://sites.google.com/site/buildagadget/nunchuk_usb/hw_elec_nunchuk/nunchuckUSB-v13.brd
Schematic and board are referenced here: https://sites.google.com/site/buildagadget/nunchuk_usb/hw_elec_nunchuk