Now lets create a pole vector constraint for the knee. Create a locator, Create > Locator, and name it "KneePV" and place it just in front of the knee joint. Once it has been placed, freeze it's transformations by going to, Modify > Freeze Transformations. This just resets everything back to 0, and keeps everything fresh and clean:) Now select the Locator and then shift select the "KneeIK" handle (in that order) and go to, Constrain > Pole Vector. This will create a Pole Vector constraint for the knee. The purpose of this constraint is to keep the knee in place, so when you bend the knee to an extreme position, the pole vector constraint prevents the knee from clipping.
Cool, now the IK handles are done! Now we move on to the grouping part.
3. Grouping the IK handles
Okay, now we will do all the grouping of the IK handles. We group all the IK handles so that we can key the groups instead of keying the actual IK handles. Firstly, switch to a perspective and hypergraph view, that way we can select all our ik handles in the hypergraph. Switch to Persp/Hypergraph by going to Panels > Saved Layouts > Persp/Hypergraph. Once it switches to the view, in your hypergraph, hit the A key. This will frame all the objects in the scene within the hypergraph window.
Lets begin the grouping. In the hypergraph, select the KneeIK, shift select the AnkleIK and shift select the ToeIK and group them (CTRL + G). Name this group "HeelRotate". You can rename objects in the hypergraph by selecting the object and then hold down the CTRL key and double click on the object. Now, move the HeelRotate groups pivot point to the heel joint. This is done by pressing the Insert key and moving the pivot while holding down V on your keyboard (holding down V on the keyboard enables the point snap). Once you have moved the pivot point, press the Insert key again to leave the "edit pivot mode".
Group the HeelRotate group again (CTRL + G) and call the new group "FootRotate" and move it's pivot point to the Toe joint..