Can passenger plane do an aileron roll and fly upside down? I've researched this topic and as far as I can tell any plane can fly upside down if it's already in this position. It just needs to be angled enough so that its wings are angled upwards. I believe Boeing 777 can do this although I can't find any video proof. 

But my real question is whether Boeing 777 can do aileron roll. From my understanding plane needs to pitch upwards a bit to gain altitude and then start to roll sideways. While doing this it will loose all lift and starts falling downwards until it is upside down and gains lift again. What are the requirements for this? What is the minimum speed it needs to achieve before attempting the roll? Is Boeing 777 structurally sound to survive the attempt? I imagine it was not designed for this but is it possible?

And a bonus question: can you link me a video of any bigger sized plane doing that?
In fact this has been done before.  A well documented case is of "Tex" Johnston rolling a 707.  In general airliners cannot do sustained inverted flight as they lack a fuel system (and lubrication system) for sustained inverted flight.

A barrel roll is readily executable. Youtube has a video of Tex Johnston doing a barrel roll.  
                
            

Edit: I gave a quick answer and felt guilty about it. There is more to the story. The OP talks about aileron rolls. An aileron roll is a maneuver where the plane does not substantially change altitude. The G forces will be negative at some point, and it is more "violent" than a barrel roll.  A barrel roll is a maneuver where the plane is rolled about the longitudinal and lateral axis, if you will, a loop and a roll in one.  Properly executed the barrel roll is a positive G maneuver.

Years ago, when I was young and some old geezer was teaching me aerobatics, he would climb into the plane with a full cup of coffee.  My job was to get to the practice area, and execute some maneuvers, including barrel rolls in each direction, without spilling his coffee.