If you need to update the when an item was posted to del.icio.us, for example if you want it to reflect the last time the post was updated etc. Then there are 2 ways this can be performed.
The first, official way is to use the official API (see http://del.icio.us/help/api/posts )and use https://api.del.icio.us/v1/posts/add? and use the &dt argument to set the date and time.
The second way is to use the FireFox browser when the "Web Developer" add-in and doing:
1. click on "edit" in the list of your bookmarks and select "full-screen edit";
2. on the web developer's toolbar select "Forms | Display Form Details", which displays the hidden fields.
3. find the hidden text in a box "<input name="date">", the field to the right of this is the posted date
4. retype this date, ensuring it is in the same format (yyyy-mm-ddThh-mm-ssZ)
5. sumbit the form in the usual way by clicking on "save"
p.s.
Now that del.icio.us has upgraded its site and become delicious.com this second method no longer works, and the only way is to use the API.
