How to prevent iTunes from trashing older versions of apps on updates?

Recent versions of iTunes have incorporated a new behavior which is to automatically move any previous version of a mobile app to the trash when those apps are updated. As far as I can tell, there is no setting to for the user to change this behavior.

I do not want iTunes to automatically throw away all older versions of my apps. Frequently, mobile app updates are buggy or remove functionality and I want to retain the ability to regress to previous versions. I, also, do not want to have to continue repeatedly dragging hundreds of apps from the trash back into my Mobile Applications folder.

What can I do to prevent this automatic trashing of my apps? Is there a way to change this setting through the Terminal? Or an AppleScript that will override this behavior?

I solved this by setting up a folder action using Hazel to automatically move any file in the trash with the extension .ipa or which is otherwise recognized by the system as a Mobile App to my iTunes/Mobile Applications folder. I'm sure you could set this up without using Hazel, just using folder actions. You will need to make invisible files visible before setting the action so you can at Trash as location A.