Well, I was hoping that the Android Debug Bridge would do us the favour, because Sony was nice enough to not change the method of entering the test mode - it's the same procedure as for the T1.
But when selecting "Switch ADB" I get "Sorry, this funtion is not available". So either there is something different with the T2 or the Wiki entry is wrong or at least misleading, and it isn't possible to start the Android Debug Bridge Daemon on an unmodified device.
Could anyone check and confirm with an unmodified T1, please?
I suppose that it might be necessary to run porkupan's enable-adb first to make "Switch ADB" work which - again - isn't possible without root access - chicken-and-egg problem.
EDIT: Yes, this thread
seems to prove it. A pitty.