Today I have tried adding my PayPal account to my iTunes (installed with Wine) Account but discovered, that adding my PayPal account as a payment method didn’t work. After inspecting the network traffic, I found that my browser (Firefox) was redirected to an itmss:// URL, but Firefox didn’t know how to handle that and did nothing. To get it working yourself, follow the next steps:

Assuming you already have iTunes installed and are using Firefox, open about:config in Firefox, accept the prompt, right-click and select New -> Boolean. In the dialog enter network.protocol-handler.expose.itmss as preference name and select false as value. After that, restart Firefox.

Next, create a new file somewhere (I chose /usr/local/bin/), called for example itunes-url and make it executable (chmod +x filename). Put the following content into the file while adjusting the paths to the Wine prefix and the installation directory.

env WINEPREFIX="/home/luca/.wine_itunes" wine /home/luca/.wine_itunes/drive_c/Program\ Files/iTunes/iTunes.exe /url "$@"

I found this invocation with Wine regedit.exe under HKEY_CLASSES_ROOT\itmss\shell\open\command, based on this website.

Then you can go into iTunes and add your PayPal payment method. Once you’ve logged in and accepted the PayPal prompts, you should get a popup from Firefox where you should select the application to handle the itmss URL. Select the itunes-url script, you created before and click “Open link”. Now iTunes should get the URL from PayPal and you can confirm the new payment method in iTunes.

Have fun!