FOR AUCTION FACTORY 1.4.0 USERS  and above - since 1.4.0 expire hour and expire minutes are introduced. Therefor we need to setup two types of cron jobs: daily and every x minutes. The daily job will send out notifications about upcoming finishing auctions and cleanup some databses. The minute job will check expiration of the auctions every x (you decide) minutes. Auction will expire at the time set up for them anyway, just the notifications will be sent through this cron job. So a timeframe of 5 minutes would be sufficient in most cases

 The minute job should be started like this

 lynx -accept_all_cookies -dump 'http://[yoursite]/components/com_bids/cron_action.php?pass=[yourpass]'

 the daily job like this:

lynx -accept_all_cookies -dump 'http://[yoursite]/components/com_bids/cron_action.php?daily=1&pass=[yourpass]'

And uncertainties please feel free to ask in our forums