Adding additional functionality to comments.php/wp-commentspost.php

Hello!

I am in the process of integrating my Simple Machines forum software with my WordPress blog. Everything has worked out fine so far, but I’ve managed to run into one single problem that won’t seem to resolve itself.

You see, I’d like for my forum users to be able to comment on my blog under their forum nicknames. I’ve set everything up so that the current user’s username is stored inside a variable, but whenever I inject this variable into WordPress’ commenting script, the comment author’s name reverts back to Anonymous.

So yeah to rephrase, I’d like to know how to replace the comment author’s username with a predefined variable.

Thanks!