Here are the necessary steps you have to take:
- Ask the clients to install Icenium Ion from the App Store.
- Open your application in Mist and produce a QR code for the application via the run menu. More info here.
- Send the QR code (or right click on it and copy the link it points) to your clients and ask them to open it.
- Make modifications you your source code and ask your clients to take your latest changes with the 3 fingers gesture.
Will this workflow going to work for you?