Action key (Ctrl) Red Rocket
Use Item (Alt) Blue Banger
Left Arrow Yellow Roman Candle
Right Arrow Green Catherine Wheel
I would watch the colors go by once without trying to hit anything and just write down the sequence. It might be green, red, yellow, red, red and so on. I can't recall the exaci sequence and don't know if it changes from game to game. I do know that it stays the same every time you try it - so you will remember it after a while.
One thing that helped me beat this was to ignore the names of things and just memorize the color sequence.
For instance the last three are red in my game - which is the key "ctrl" 3 times. Also make sure you don't hit the button that goes to that color until the color hits or enters the green area of the bar. When two or three are close together - I wait for the first to hit the left edge of the green area and then hit the rest as they enter.