I recently had to reinstall all my CX apps and found the Audible has updated the Audible Download Helper App. The new update will not install under CX 4.2. It gives a non-descript error saying that the installation failed. Interestingly enough it successfully installed and ran on wine version 20050725. The program did work but the fonts in wine were so poor quality it was almost impossible to read the interface with the high screen resolution(1280x1024) I use.
So I copied the installed folder under wine into the CX fake window folder. I then set created an audio file association for the aw_dhelper.pl file name. And set that file association to execute the follow string. Now I can save the aw_dhelper.pl file to disk and click on it and the audio book will automatically download into iTunes.
"/opt/cxoffice/bin/wine" --check --bottle dotwine --cx-app "C:////Program Files////Audible////Bin////ADHelper.exe"
You will need to replace "/opt/cxoffice/bin/wine" with the location of where you installed CX.