To set the date for a blog post to something other than the file's creation date, use the Meta plugin and a trick or two. What seemed to work most of the time was:
This doesn't change the timestamp on the filesystem, but will (eventually) change the timestamp in dokuwiki. You can also use a touch command to change the filesystem date ala:
touch -t 200710172225 24_hours_of_moab_article_from_the_aspen_daily_news.txt