Could trackbacks be enabled by simply adding an argument t=y (trackback equals yes) to any permalink?
If this were the case and you wanted to use trackback to post a remote comment about something, you could select the trackback link and then use a bookmarklet to blog the post and trackback at the same time. In order to stop browser referals from showing weblog referer urls would have to have a similar parameter, say ?dt=y (display trackback equals yes) as part of the permalink. A script would check for qualified referrals. (A trackback to a permalink that also could track to another site would be called as ‘permalink?dt=y&t=y’)
e.g.
https://www.davidgalbraith.org/archives/000486.html#000486?t=y