With very little progress with the camera (I can make shots with fswebcam, but when streaming with mjpg-stream, all frames are empty), I decided to go back to the mechanical part and see if it actually walks. I measured the legs, put it all into the inverse kinematics and copied the code for the creep gait from µKubik. Turned out I need to do some more fine-tuning of the trim and reverse settings in my servo controller, but it finally walked:

It's still pretty slow, and the cable makes it unbalanced, but the basic idea is there.

Now back to getting the camera to work. In the worst case I guess I will just stream the shots made with fswebcam... I wish I had OpenMV for this robot brains.