Drupal Cron, php-cli andmulti-site install

Hi,

We have a video-oriented Drupal 5 multi-site install with cron jobs that could potentially take over an hour (transcoding video and pushing files off to a CDN). I would like to run these via php-cli, so that I can change max_execution_time to something absurdly long in /etc/php5/cli/php.ini rather than /etc/php5/apache2/php.ini.

Of course, as I've learned through digging around the forums and Google, executing cron.php with php-cli only works for the default site out of the box.

Has anyone figured out a way to do this in a multisite install?

I've tried adding to bootstrap.inc something like

if ($_SERVER['USER'] == 'cron_user') { // if USER is cron_user, we are running this from cli

$_SERVER['HTTP_HOST'] = $argv[1]; // take variables from command line
(... populate rest of $_SERVER to match what I get calling cron.php via wget ...)
}

and cron.php executed without any errors, but my status report did not reflect cron having run.

Any ideas would be greatly appreciated.