Bones-on-curve Spine Tutorial question

I’ve tried to follow the Bones-on-Curve Spine tutorial that’s posted here, but I’ve got stuck towards the end.

At the end it says:IK constrain each bone to the empty at its tip. You can do this quickly by selecting the empty first and then Shift+RMB selecting the bone, and then pressing Shift+I. Make sure you change the ChainLen value to 1 after each IK assignment.

I have 2 problems:

  • I’ve tried selecting an individual bone with Shift+RMB (actually Shift+LMB for me as I’ve flipped LMB/RMB), but it selects the whole armature. I can’t find out how to select the individual bone.
  • Pressing Shift+I seems to do nothing.

Is there an alternative method to using these shortcuts? What is it actually trying to set up?