Autoloaders are strictly .exe files designed for Windows.
The progress bar on his computer began to crawl. Percent by percent, the "Jakarta" firmware—the Z3's internal codename—was being reconstructed. When the phone finally vibrated and the classic BlackBerry logo appeared, Elias didn't just see a home screen; he saw the culmination of a successful Developer Autoload
You can find historical and developer-specific autoloaders through these community archives: