Create your External Device as a Control Surface. That'll give you a blank device and a LEARN button.
Press each of the Stomp pedals consecutively, then operate each Exp Pedal, then go to Bank 18 and press pedals 8 (for the Tuner) 9 (Preset Prev) and 10 (Preset Next). This will add controllers to the Control Surface.
The reason there's no track for the FCB is because S1 uses a different method. Instead of using a MIDI track to receive the messages, then pointing the Output of that track at the VST on an Audio track (Cakewalk) or the track with whatever VST (Reaper, LIVE!), the Control Surface receives the MIDI messages. You then press/operate the FCB pedal which activates the related Control Surface knob/switch, and do whatever in the VST starts the assign process. With the native S1 plugins that means to right-click the plugin UI control you want to assign and select "Assign "X" (control name) to ControlY on FCB" (name you assigned to the Control Surface when you created it) as in my screenshot.
The question when doing this with Amplitube will be - do you operate the FCB pedal BEFORE you select the UI control (as with the S1 plugin) and LEARN or do you do the reverse as would be normal with any of the other DAWs?
You'll have to try both. Let me know what works. If I liked S1 at all, I'd buy it to try, but giving me a crippled "DEMO" was strike one.