Let me make sure I understand this - you want to be able to have an image be uploaded when it is pasted into the WYSIWYG editor from anywhere yes?
If so, it's flat out impossible - for security reasons javascript cannot read image data from the clipboard of the host OS or read a file's contents without going through the browser's file input control. You must upload the image as a separate action, and no vendor can provide you otherwise unless they also rewrite your browser.
Note, this *might* be possible using ActiveX controls in IE, but ActiveX is the sourcepoint of 95% of IE's security flaws and it is highly recommended that you turn it off, leave it off or, better yet, don't use IE.
Sure, it's a stretch to get copy/paste from the hard drive.
I'd love that, for copying/pasting from Word etc.
But it's not neccessary.
Most of my discussion pieces exist on the net.
My discussion emails.
My own weblog articles and posts.
Those are all hosted on the net.
Same goes for my team-mates.
Microsoft's OneNote has a powertoy that can export NoteBooks as websites.
So I'd simply have to upload those to my site.
Once hosted, I could copy/paste whatever's relevant into Vbulletin.