I doubt that an automatic schema conversion would really help you as some stuff just works too different between the two databases. An automatic migration can leave you with the false security of having ported your code successfully.
What I'd try is to feed the MySQL schema into postgres (after removing the awful ` quotes around field names) and see what happens.
In cases where postgres doesn't accept the MySQL schema dump, you will have to manually check what you are doing and fix it manually anyways (the exception being auto_increment which you can fix with an easy search and replace process).
Stuff like that "timestamp not null default '0000-00-00'" comes to mind for example. I wouldn't know whether I would drop the invalid default or both the not null and the invalid default - that pretty much depends on the application.
