Can i do this?

[M i K e]

I was wondering if there was a Mod that allowed you to post a thread under a different user. The reason I ask this is that I am hosting some SMF forums on my site but I want to move over to my vB forums, now the members might get annoyed if there posts go so I was wondering if i could re-post the threads etc under their usernames.

Edit: I have found the "change thread owner" mod, this would still involve me copying and pasting all the threads then manually changing the owner, is there one that allows me to post under a different user?