Receiving WM_COPYDATA in Python

I am trying to read from Python the WM_COPYDATA message some applications (I'm trying with Spotify) send to WindowsLiveMessenger to update the "What I'm listening to..." phrase.

From what I have been able to find, WM_COPYDATA messages come in a COPYDATASTRUCT with the following structure:

• dwData in our case 0x547 so that it access the listening now feature
• cbData with the length of the string received
• lpData with a pointer to the string itself, may include Unicode characters

The string should have the following format: \0Music\0status\0format\0song\0artist\0album\0 as stated by ListeningNowTracker

What we receive in a WM_COPYDATA event is a pointer for lParam that contains the COPYDATASTRUCT.

I started tinkering with pywin32 functions and I remembered that they do not accept Unicode characters from past experience, then I switched to ctypes. Despite this being an almost new world in Python for me, I tried with POINTER() and all I got was unknown objects for me or access violations.

I think that the code should create a COPYDATASTRUCT:

class CopyDataStruct(Structure):
    _fields_ = [('dwData', c_int),
                ('cbData', c_int),
                ('lpData', c_void_p)]

Then make the lParam be a pointer to that structure, get the string pointer from lpData and finally get the string with ctypes.string_at(lpData,cbData).

Any tips?

UPDATE 1

The WM_COPYDATA event is received by a hidden window built with win32gui just for this purpose. The copydata event is connected to a function called OnCopyData and this is its header:
def OnCopyData(self, hwnd, msg, wparam, lparam):
The values the function delivers are correct as compared with the ones from the Spy++ messages log.

UPDATE 2

This should be close to what I want, but gives a NULL pointer error.

class CopyDataStruct(ctypes.Structure):
    _fields_ = [('dwData', c_int),
                ('cbData', c_int),
                ('lpData', c_wchar_p)]

PCOPYDATASTRUCT = ctypes.POINTER(CopyDataStruct)
pCDS = ctypes.cast(lparam,  PCOPYDATASTRUCT)
print ctypes.wstring_at(pCDS.contents.lpData)