I've updated the modem scripts for the 8100, 8700 and 8800 to work with the latest release of OS X. You can grab the new scripts (one package for all phones! Yay!) and read the new install instructions over here:

Updated Modem Scripts for OS X 10.5 (Leopard) - Fibble.org

As always, let me know if you run into problems and I'll help if I can.