Easiest way is via composer. Just run composer require codenamephp/deployer.crontab in your cli which should install the latest version for you.
Just install the package and use the task in your deploy.php, e.g:
$deployerFunctions = new \de\codenamephp\deployer\base\functions\All();
$deployerFunctions->registerTask(new \de\codenamephp\deployer\crontab\Task\Install()); //expects file in {{release_or_current_path}}/crontab -> crontab {{release_or_current_path}}/crontab$deployerFunctions->registerTask(new \de\codenamephp\deployer\crontab\Task\Install('path/to/file')); // crontab path/to/file$deployerFunctions->registerTask(new \de\codenamephp\deployer\crontab\Task\Install('path/to/file', 'deployerUser')); // crontab -u deployerUser path/to/file$deployerFunctions->registerTask(new \de\codenamephp\deployer\crontab\Task\Show()); // crontab -l$deployerFunctions->registerTask(new \de\codenamephp\deployer\crontab\Task\Show('deployerUser')); // crontab -u deployerUser -l$deployerFunctions->registerTask(new \de\codenamephp\deployer\crontab\Task\Delete()); // crontab -r$deployerFunctions->registerTask(new \de\codenamephp\deployer\crontab\Task\Delete('deployerUser')); // crontab -u deployerUser -rvendor/bin/dep crontab:installvendor/bin/dep crontab:showvendor/bin/dep crontab:delete