Move Threads/Users/Posts from one forum to another and keep db id's

[j0rd]

Here's my issue. I've got a 4 year old vbul 3.1 version installed. It's a mess. After 4 years you get a pretty disgusting database with old unused mods.

We've developed a new version of our forum on 3.6 and we'd like to import all the old forums, threads, posts, pms, avatars and all that jazz into the new clean install.

As far as i know there are two ways of doing this. Niether of which will work for us.

Impex :
- Problems: Doesn't keep threadid's, userid's and all that stuff. That will not work for us.

Database Import:
- Problems: This will not work since the DB structures are different.

How can i do about importing all my data, but keeping the proper IDs for everything? I would assume this is a common task, but i'm not able to find any information on it.

PS. We have a really large board. Impex took over 12 hours the first time we tried. Not fun.