According to some Mac-Teddy users (I do not have Mac),
Teddy runs on 
Macintosh internet explorer 4.5 
 
and
apple MRJ applet runner
 
Please download the programs, and
open teddy.html from them.
They seem to sometimes work and sometimes not...
In order to save a model, you need to run Teddy as an independent program, instead of running it on Internet Explorer. You should run "JBinary" (included in MRJ), and open "teddy.Teddy.class" in "teddy.jar". MRJ is avaiable at http://developer.apple.com/java/ .
if you find any additional information, let me know.
Notice:
Sorry, but please refer to other resources 
if you need to know what "java" and "MRJ" mean...
Takeo Igarashi