We've used a script for quite a while now that is executed every few minutes (not from a trigger -- it uses a counter) that was modified from the Perforce review daemon script. This in itself was pretty easy to set up. As far as incorrect information is concerned there are two possibilities:
Missing a case number: the web query to add this is actually pretty trivial and can executed quite easily after a changelist has been modified (or completely manually).
Incorrect case number: this would require an edit to the FB database to remove the incorrect case number. The correct correlation can be made as in the previous note. We didn't go with the P4DTG solution because of
- when we set this up, there were server conflicts and
- the extra FB user required for its usage.