You can implement this by adding a demerit button. If a member can rank up through a thousand merits, they should be demoted through a hundred De-merits. This could be open to members or assigned to moderators. You may also bestow demotion powers to intelligent reputable members like LoyceV, Yahoo62278, Notatether, Moccaccino, Logfiles, Suchmoon and others.
I won't go into the usefulness and complexity of implementing something like this, but it would be a big mistake to enable such features only for certain members. We already have many complaints and discussions that the DT system is unfair because it seems as if certain users are privileged. That would only bring more unnecessary drama.
The current trust system is not perfect, but it is functional for the most part, although some users continue with their behaviour regardless. Demerit or demotion will certainly not affect such.