python from excel

xlrd, xlwt, and xlutils are fine for accessing excel files from python, but what about accessing python from excel (like calling out to vba hooks to define user functions)? pyxll seems to do what i would want (even claims numpy, ctypes, and cython support!), but the license seems very restrictive. if there is nothing better, it is probably the way to go. i might also check out the ironpython hook (http://www.ironpython.info/index.php/Interacting_with_Excel) and discoveryscript (http://www.xefion.com/discoveryscript.html). discoveryscript is free, but i think its license will also restrict redistribution (and the other products on the website are in the $500/licence range), so that might be problematic.