Adding field, but NOT on user profile, -> on the post messaeg page

[Sharg]

Hi
i'd like a new field to be displayed on the page where users can enter their messages.

This field would be (in my case):
"Author" (not the board's post author of course) that would be just bellow the [Check message length link] and users would enter what they want here in relation to the lyrics author about what they are typing

Requirements:
-Info entered in this fied when the message was posted should then be displayed on forumdisplay page

-Field should be included in searches

Any way to do this ?

Thanks,
Sharg