This piqued my curiosity. The answer would seem to be that it's not supported. On a normal device, you can do this to suspend to memory and wake up in 10 seconds:
Code:
sudo rtcwake -m mem -s 10
On a Kobo, you get this:
Code:
# rtcwake -m mem -s 10
rtcwake: /dev/rtc0 not enabled for wakeup events