The mechanical dimensions of the ATNGW100 are given here. There are 3 expansion headers available - J5,J6 and J7. The pinout details are given here. I want to gain access to the PWM channels - so I decided to go with J5. An old hard disk cable came handy.
A few neat configfs tricks later, we are ready to blink LED's!
More GPIO related info here.
By the way, is it the end of the road for ioctl's?
Things to do immediately: read the gpio driver, write a PWM driver.