need to change the postdate to get it the first post of an thread

[infinityloop]

more and more times i am facing this issue in our forums.

example:

1. we start an thread where we request some softwaretesting
2. we get results + find an other issue which needs its own thread
3. now i start an new thread for this new issue and move the related posts from the other thread to the new one

the problem now is that my initial post in the new thread becomes the last because of the post-time/date.
but i need my post with instructions to be the first one.

is there any hack around which allows me to change the posttime/date?

thanks!
chris