I writed scripts for POL all last week and I have some suggestions:
1. So as some time ago POL can't properly unpack different wine versions, that will be better if you' ll add checking for wine version directory if it's empty. Because many games didn't work with another wine versions and if directory is empty, POL uses default system wine version. You can check my example in TrackMania script: http://www.playonlinux.com/en/topic-1528-TrackMania_Nations_Forever.html
And you can add this check if user try to reassign wine version from POL GUI.
2. Some games use DirectX. And if user with LiveInstall or from script, installs it, he allways have to download it again and again. Can you, please, add something like local repository for that case. For example I make LiveInstall than choose install DirectX, POL check for last version on site and compare it with local repository version. If all is ok user get local installer, if you renew version or user didn't download it ever, he have to download DirectX installer.