Open the Registry Editor: Simply type "regedit" in the Win7 Startbar Search Window.
Then within the Reg Editor browse to:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Telltale Games\BackToTheFuture101.exe
In the Window where you see the Registry Entries like LanguageID, Version and stuff like that you have to create a new String Value. Just right click -> new -> String Value.
Name it "language". After it's created simply double click it and change the Value to "english" or whatever Language you want to have for the text. I think only english, german, and french are working but i'm not sure about that!
Now you can play the Game with English text
