Inserting text (dynamically) in wysiwyg editor

[MarkPW]

I've inserted vB's wysiwyg editor on my profile editing pages to allow members to use bbcode easily. However, I want my own function to dynamically update the text editor with (user prompted) text. This is not a problem when the editor is in non-wysiwyg mode, but in wysiwyg mode I can't seem to update the text via Javascript, and I wondered if somebody knew which of vbulletin's JS functions might assist me in achieving this?

Thanks for any help