If you look at the functions in wp-includes/cron.php, it seems fairly obvious as to how to use it.
$timestamp will be a timestamp as returned by any of the php time functions.
$hook would be the name of an action hook you want triggered at that time.
$args would be arguments you want passed to your functions.
$recurrance appears to be either ‘hourly’ or ‘daily’.
You can call functions to set one time events, to set recurring events, to change schedules for recurring events, to unset events entirely, to find out when recurring events are going to be run, etc.