This post has ended up in the iChat Community.
It seems to relate to iChat Theatre which can display as the Video feed different type of document.
1) Is what you are writing on the computer ?
I.e. TextEdit, Keynote or Powerpoint or Word Document
If so use the iChat Theatre item in the File Menu and navigate to the file.
This will use QuickLook to display the item as the Video feed.
2) If you are pointing the camera to a piece of paper that has something written on it it will depend which version of iChat you are using.
Up to iChat 4 (Leopard OS X 10.5.x) you could use this Utility http://www.ecamm.com/mac/iusbcam/ which has a Flip ability.
In Later version you have to take a pic in PhotoBooth and flip it there and then Share it in iChat afterwards.
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.2)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images." No, Seriously