I'm new to win32com, so I don't know if this helps... try to start Excel with:
xlApp = win32com.client.gencache.EnsureDispatch("Excel.Application")
This should run makepy, and you can find some resulting Python files in ...\Lib\site-packages\win32com\gen_py\00020813-0000-0000-C000-000000000046x0x1x7 (last folder might be another name for you, I dont know). Check the init.py file, there's a bunch of constants defined there.
Edit: you can access these constants with:
from win32com.client import constants as c
Edit2: path to folder:
win32com.__gen_path__