Sorry for posting twice in a row, but to expand on the above, I've now finished and released Issue 1.0 of my
vBulletin (3.x) Comments addon for Coranto (available
here).
It ports the existing functionality from the vB2 compatible version and updates it for vB3 allowing comment threads to be created in vB direct from the news editing pages of the Coranto CMS. Additionally, I've added a couple of extra configuration parameters to handle the situation where a table prefix is used when installing vB and also to default the creation of vB threads from each news item.
It's only been tested with Coranto 1.24 and vB 3.0.7 so if there were any table changes in earlier 3.x versions of vB there may be 'issues'. (I also don't know what it will do with 3.5 as I haven't looked at the format for that at all).