I thought to change line 625 \includes\modules\shipping\ozpost.php

$db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, date_added) VALUES ('Cost on Error', 'MODULE_SHIPPING_OZPOST_COST_ON_ERROR', '25.00,99.99', 'If an error occurs these Flat Rate fees will be used (The First value for Australian delivery. The second value for Overseas delivery.</br> A value of zero will disable this module on error.)', '6', '20', now())");
similar to

$db->Execute("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, date_added) VALUES ('Cost on Error', 'MODULE_SHIPPING_OZPOST_COST_ON_ERROR', '10.00*[Weight],20*[Weight]', 'If an error occurs these Flat Rate fees will be used (The First value for Australian delivery. The second value for Overseas delivery.</br> A value of zero will disable this module on error.)', '6', '20', now())");
However I have yet to work out how to call up the [Weight].