Fix for metaclass conflict. Get the latest snapshot of comtypes from svn. Run 2to3.py refactoring. Then apply the following patch. (Tested with Python 3.3.2/Windows 8/x86).

0001-Comtype-Fix-metaclass-conflict.patch

---
 comtypes/__init__.py   | 8 ++++++--
 comtypes/automation.py | 4 +++-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/comtypes/__init__.py b/comtypes/__init__.py
index 6590ead..fa604af 100644
--- a/comtypes/__init__.py
+++ b/comtypes/__init__.py
@@ -268,7 +268,9 @@ class _cominterface_meta(type):
         _pointer_type_cache[cls] = p

         if cls._case_insensitive_:
-            class p(partial.partial, p):
+            class _meta(type(partial.partial), type(p)): pass
+
+            class p(partial.partial, p, metaclass=_meta):
                 # case insensitive attributes for COM methods and properties
                 def __getattr__(self, name):
                     """Implement case insensitive access to methods and properties"""
@@ -292,7 +294,9 @@ class _cominterface_meta(type):
                                        self.__map_case__.get(name.lower(), name),
                                        value)

-        class _(partial.partial, POINTER(p)):
+        class _meta(type(partial.partial), type(POINTER(p))): pass
+
+        class _(partial.partial, POINTER(p), metaclass=_meta):
             def __setitem__(self, index, value):
                 # We override the __setitem__ method of the
                 # POINTER(POINTER(interface)) type, so that the COM
diff --git a/comtypes/automation.py b/comtypes/automation.py
index f8bb80d..5108291 100644
--- a/comtypes/automation.py
+++ b/comtypes/automation.py
@@ -515,7 +515,9 @@ del v
 _carg_obj = type(byref(c_int()))
 from _ctypes import Array as _CArrayType

-class _(partial, POINTER(VARIANT)):
+class _meta(type(partial), type(POINTER(VARIANT))): pass
+
+class _(partial, POINTER(VARIANT), metaclass=_meta):
     # Override the default .from_param classmethod of POINTER(VARIANT).
     # This allows to pass values which can be stored in VARIANTs as
     # function parameters declared as POINTER(VARIANT).  See
--