I haven't tried it, but I don't see why not. The BCM code is written in python and I expect it to be portable. I'm not sure if the standard installation packages will go straight on, they are marked 'noarch', but I have to say I've not tried it. One thing you might want to research is whether usb-modeswitch will function OK under PowerPC. PowerPC is a big endian platform and x86 is little endian, usb-modeswitch works with sequences of bytes that are sent to the modem to switch it from storage mode to modem mode.
If you do decide to take the plunge, let us know how you get on,