OK, solved with the Cheat Engine. Warning: a free license expires after the first run, so use it wisely. (it is free, idiot me is).
You need to:
1) Run the Cheat Engine program and leave it open.
2) Start a game and load the anal probe minigame
3) Switch-window to the Cheat Engine (alt+TAB)
4) open a process "South Park (...) .exe
5) click on a checkbox "Enable Speedhack" and set it to 0,2. This will slow down time 5x.
6) switch back to a game and beat the mini-game (easy)
7) again, switch to Cheat Engine and disable a speedhack
return to a game and save after passing a check point