It is possible to drive the WeDo from Python on a Mac, without a kext. I've only tested motors since I don't (yet) have the other sensors. You need to access the USB HID device directly. There are a couple of prerequisites to install:
You'll likely want XCode and friends installed to be on the safe side.
There are a number of forks of cython-hidapi available so your mileage may vary depending on which version you use. I don't remember installation being problematic.
Once those are installed and your WeDo is plugged in you can do something, at a minimum, like:
# vendor id, product id:
dev = hid.device(1684, 3)
# turn both motors on
# HID format is reportID, message type, data1, data2, ...
dev.write([0x0, 0x40, 127, 127, 0x0, 0x0, 0x0, 0x0, 0x0])
# turn them both off
dev.write([0x0, 0x40, 0, 0, 0x0, 0x0, 0x0, 0x0, 0x0])
The changes to get WeDoMore to use hidapi instead of generic usb on a Mac don't look to be too onerous. If I manage to get something committed I'll update my answer with a link.
[Edit: I've committed a fork of WeDoMore that adds support for motors on the Mac here. Again, I'll update if the pull request gets accepted]
Small side-note: The WeDo can also drive 9v motors with the correct converter cable. I think it's possible to read the RCX sensors as well, but mild soldering may be required (see, e.g. here for a proof of concept). But if the WeDo can be fooled into reading the devices then Python can be used with those other sensors.