I still believe it is possible to get the Kõu USB device to work on Macs.
The FTDI serial driver may not be necessary – Apple has its own USB serial drivers. I’d like to try out patching IOSerialFamily.kext/Contents/PlugIns/AppleWWANSupport.kext/Contents/Info.plist with the ZTE USB modem’s vendor and device ID’s and see what happens.

Now I only need to get my hands on a MacBook to try that out 😉