To delete the previous MAD plugin dll, you'll need to browse the wineskin wrapper you've created. Select "Show package contents" from the context menu on your MediaMonkey wrapper, then drive_c/users/your_username/Application Data/MediaMonkey/Plugins and delete in_mad.dll from this folder and any other MAD plugin/ini files. Or you might have it in drive_c/Program Files/MediaMonkey/Plugins if you haven't installed it via the script.
Then follow the last step in the build instructions (which is what I used to create my MM wineskin) found on page 5 of this thread :
* Use Tools->Extensions. Click "Add" and browse to the MAD plugin (inmad.mmip) which can be downloaded from http://www.mediamonkey.com/addons/brows ... ut-plugin/ . Close and then restart MM.