Yes, you can add a game to Steam and use the In-game feature.
At the very top of the Steam window, press on Games, then click on "Add a Non-Steam Game to My Library".
A window should pop up. Press on "BROWSE...". Now you need to find the AssassinsCreedRevelations.exe that starts the game. By default it's in Program Files/Ubisoft/Assassin's Creed Revelations.
When you find it double click it, then it should appear in that Steam window as ticked. Now just click on "ADD SELECTED PROGRAMS" and then start the game from the Steam Library.