Product review (5 stars): Not exactly high quality, but if you need it, you need it.
I wouldn't exactly give this 5 stars for quality, but if you have a washer that needs it, you need it :)  And amazon's price is way better than the official GE parts site.

It's super-easy to replace.  Unplug the washer, use a nose-pliers to remove the clip that holds the knob on (if you just pull hard, you'll probably break it, I bet that's why other people bought those parts too!).  Unscrew three 1/4" hex screws behind the front panel.  Angle it away from the back and slide it to the right to unhook it from the bottom.  Unscrew one screw holding the timer and unplug the big plug from it (there's a springy catch you have to squeeze.  Replace with the new timer, reverse everything you did, done.