Indeed, in the meantime, you can play around with command line options
to alter the amanda.conf parameters:

http://wiki.zmanda.com/index.php/Amanda#CONFIGURATION_OVERWRITE

First run amdump to holdingdisk, setting the tapedev to e.g. /dev/notape
(do not use /dev/null -- amanda assumes tapedev /dev/null is for testing
purposes and makes a backup, and trows it away).
Then run amflush using the paramaters in amanda.conf