In short:
VCC Pins:
19, 20
GND Pins: (take your pick) :)
1, 2, 33, 34, 47, 48, 69, 70, 73, 74, 77, 78, 81, 82, 85, 86, 89, 90, 93, 94, 97, 98
Channel A:
46
Channel B:
42
With this, I am assuming the ChannelA and Channel B are TTL, and not differential, and you also dont mention an Index for the encoder.
Hope that helps.
SMEAC