This extension was no longer maintained by the Magento team. It was provided only for backward compatibility and is not tested with recent Magento releases.
We made it Magento 1.7 compatible and have successfully migrated one osCommerce store with customer, order, product and category data.
If you're interested to contribute, feel free to do so ;-)
Just copy the app folder to your Magento installation.
In your Magento backend go to System > Import/Export > osCommerce and add a new osCommerce profile and run it.
Please place all images under MAGENTO_ROOT/media/import/ with writable permission to all files including sub folders. To import orders, Magento requires that customers also be imported.