To launch the Sign-in Kiosk before a service, first retrieve the URL from the Web Terminal pane in MSP, or if you are on an iPad launch the MSP Kiosk app!
From inside of MSP, go to the Web Terminal pane on the left side of the program window and click on the "Web Terminal settings..." button at the top. In the Settings window, click on Sign-in Kiosk on the left, and here you can copy the URL for the Kiosk.
Email this to yourself or others to open on the device you will be using for sign-ins. Then on that device, simply go to that URL in any browser to begin sign-in's.
There is also an iPad app which can be found in the App Store on an iPad by searching for "MSP Kiosk."