<p>I have an application which is fully unicode compatible in Delphi 2006. I had replaced all AnsiStrings with WideStrings, replaced all VCL controls with TNT controls, and changed all string functions from AnsiStrings to WideStrings. It looks like all that work was for nothing, because I'm going to have to reverse it all. Is there anyway to Trick Delphi 2009 into thinking Widestrings are in fact UnicodeStrings?</p>

No, there really isn't. But you won't regret the work to truly Unicode enable your application.
The TNT controls can easily be replaced with the regular VCL controls.  You can do that pretty simply using the wizard from GExperts (
http://www.gexperts.org
) that replaces one control type with another automatically.
Then, you can change all your WideString declarations to regular strings.  String is now an alias for UnicodeString, and so all your strings can hold Unicode data just fine.
BTW, the author of the TNT controls, Troy Wolbrink, now vastly prefers Delphi 2009 over his own controls.