There's a php class for trackbacks that can be found
here. You should be able to make it work with geeklog with no problem.This site is for how movable type handles pings
here. I think to send a ping you should be able to send one after your story is published. Like this...
Create story
Fields: Name...body...etc...
Additional field: Is this a trackback? Click checkbox [ ]
Then the user saves the new story and if the checkbox was chosen there would be an additional step. Note the story is already saved to the database. From there the user has to fill out the ping url. The user's shown what will be passed to, in this case, geeklog.net's trackback.php. Something like
Title:
Blog Name : GeeklogWorks.com (equal to site_name)
Excerpt: [truncated if necessary]
Url: [site_url]/article.php?story=[sid(storyid)]
The user can then fill out the ping url and, click submit. From there if it was successful(if the story id exists) the xml success code would be read(you can find this code in the php class) and you can display a success message otherwise display an error message. Let me know if this is what you're asking for.