# Add a Cube
# Add two Shape Keys to it (Basis, Key 1)
# Then run this script...
import bpy
a = bpy.data.actions.new('Action')
f = a.fcurves.new(data_path='key_blocks["Key 1"].value')
f.keyframe_points.add(2)
f.keyframe_points.foreach_set('co', [0, 0, 100, 1])
f.update()
o = bpy.data.objects['Cube']
o.data.shape_keys.animation_data_create()
o.data.shape_keys.animation_data.action = a