Even I think my relply might merge the topic on "IXUS 220 USB remote control" , I post it here as a reply to the suggested action.
After installing the script proposed, I ran the code, got "waiting for USB " after STARTED, and sent 5V pulses I got following results :
-black screen for a bit more than second,
-return of camera live image,
-script stopped (need to click again for a new start),
-no expected print on screen.
Hope this can help
...and Happy New Year to all.