How can I add a vB textarea to my mod?

[Dr.CustUmz]

ok, I have tried a lot of things. too many to post, but I am not getting this.

so let me explain a little more.

the textarea i have added to newthread page (its under the message box) think of it as a sub message.

it stores its info in sql by itself and at the moment is set to no_html

now i want to return that data on the showthread page (within the original post) but with it allowing bbcode and not allowing html.

I show the variable for the "sub message" content within showthread lets say $submessage

so could I use something like

$submessage = convert_wysiwyg_html_to_bbcode($vbulletin->GPC['????????']);

in hook ???????

but the bbcode php should already be where I am trying to use this.