As announced on February 18th, a generator for DB_Table is available now. David C. Morse has put some work into this new generator script which was based on the script that PEAR::DB_DataObject offers.
Some more details about the generator, cited from the changelog:
This class generates code required as an interface to an existing database by reverse engineering the database. It generates a DB_Table subclass definition for each table, and a script that instantiates one instance of each DB_Table subclass, and a parent DB_Table_Database object. See the documentation block for the new class for usage instructions, and the tests/generator/tests.php script for an example.