The actualization of Anatta
i express anger or sadness, i should look to detach or disassociate
  myself from such emotions.


Not! Stop hypothesizing and simply observe the events/experience at their unsullied form.
When you say "I express anger", it's already sullied. You have assumed the existence of an 'I'. Anger is anger. So simply notice it as anger. Not 'I'! Same with sadness and other emotions. Don't look to do anything with them. Just observe and see if they qualify as an 'I' or 'self'. 


  Are meditation and mindfulness the only methods of actualization?


There's no actualization required. Anatta is already actual. It's similar to saying "how do I make the world round?". It's already round, you just need to realize it.
Satipattana meditation is the only way to purify the mind. Buddha called it the "Ekayano Maggo".The one and only way.