I got this achievement in a stupidly easy way. After I found the first comic book (I think that's what it was, whatever shows you more combos), I looked up the combo pattern in my menu, I think you can change it but it was like XXBBAAY for me. I just decide to screw around and hit those buttons and BAM! this achievement and the one for the 5 hit combo unlocks. I wasn't even fighting an enemy at the time.
You will need to see each attack performed in order to get credit, so may take a few attempts to get the timing down.
You can look up the combo thing in the menu at any time, but it's limited to 4 buttons until you find the first comic book it seems.