To limit the game to 60FPS (or any framerate for that matter) with Steam, follow these steps:

1. Go to your Steam Library, right click on TCOL and press "Properties...":

2. In the window that popped up add this line under Launch Options: --limit-fps=60

That's really it! Now you can close the window. To see if the changes were saved properly, you can run the game and press F2 to see your framerate in the top left: