SM Rig Corrector

import bpy, math
from mathutils import Vector

identifiers = ['L', 'R']
armature = bpy.context.active_object
new_constraints = []

bpy.ops.object.mode_set(mode='EDIT')

for b in armature.data.edit_bones:
    if b.name[0] in identifiers and '.' not in b.name:
        b.name = b.name[1:] + '.' + b.name[0]

    if 'Foot.' in b.name:
        # prep parent with slight bend
        b.parent.tail -= Vector((0, 0, 3))

        # create new IK bone
        ikb = armature.data.edit_bones.new('Foot_IK.' + b.name[-1])
        ikb.head = b.head
        ikb.tail = ikb.head - Vector((0, 18, 0))

        # and target
        ikt = armature.data.edit_bones.new('Foot_IK_Target.' + b.name[-1])
        ikt.head = b.parent.head + Vector((0, 0, 20))
        ikt.tail = ikt.head + Vector((0, 0, 10))

        # setup constraint
        ikc = armature.pose.bones[b.parent.name].constraints.new('IK')
        ikc.target = armature
        ikc.subtarget = ikb.name
        ikc.pole_target = armature
        ikc.pole_subtarget = ikt.name
        ikc.pole_angle = -math.pi / 2
        ikc.chain_count = 2
        new_constraints.append(ikc)

    elif 'Hand.' in b.name:
        # prep parent with slight bend
        b.parent.head -= Vector((0, 0, 2))

        # create new IK bone
        ikb = armature.data.edit_bones.new('Hand_IK.' + b.name[-1])
        ikb.head = b.head
        ikb.tail = ikb.head - Vector((0, 18, 0))

        # and target
        ikt = armature.data.edit_bones.new('Hand_IK_Target.' + b.name[-1])
        ikt.head = b.parent.head - Vector((0, 0, 20))
        ikt.tail = ikt.head - Vector((0, 0, 10))

        # setup constraint
        ikc = armature.pose.bones[b.parent.name].constraints.new('IK')
        ikc.target = armature
        ikc.subtarget = ikb.name
        ikc.pole_target = armature
        ikc.pole_subtarget = ikt.name
        ikc.pole_angle = -math.pi / 2
        ikc.chain_count = 2
        new_constraints.append(ikc)


bpy.ops.object.mode_set(mode='POSE')

# hack to force constraint data to refresh
for nc in new_constraints:
    nc.iterations = nc.iterations