What other suttas instruct how to do Anapanasati, apart from the Anapanasati Sutta?
MN62 Maha-Rahulovada Sutta is one of them.


  "[1] Breathing in long, he discerns, 'I am breathing in long'; or
  breathing out long, he discerns, 'I am breathing out long.' [2] Or
  breathing in short, he discerns, 'I am breathing in short'; or
  breathing out short, he discerns, 'I am breathing out short.' [3] He
  trains himself, 'I will breathe in sensitive to the entire body.' He
  trains himself, 'I will breathe out sensitive to the entire body.' [4]
  He trains himself, 'I will breathe in calming bodily fabrication.' He
  trains himself, 'I will breathe out calming bodily fabrication.'
  
  "[5] He trains himself, 'I will breathe in sensitive to rapture.' He
  trains himself, 'I will breathe out sensitive to rapture.' [6] He
  trains himself, 'I will breathe in sensitive to pleasure.' He trains
  himself, 'I will breathe out sensitive to pleasure.' [7] He trains
  himself, 'I will breathe in sensitive to mental fabrication.' He
  trains himself, 'I will breathe out sensitive to mental fabrication.'
  [8] He trains himself, 'I will breathe in calming mental fabrication.'
  He trains himself, 'I will breathe out calming mental fabrication.'
  
  "[9] He trains himself, 'I will breathe in sensitive to the mind.' He
  trains himself, 'I will breathe out sensitive to the mind.' [10] He
  trains himself, 'I will breathe in satisfying the mind.' He trains
  himself, 'I will breathe out satisfying the mind.' [11] He trains
  himself, 'I will breathe in steadying the mind.' He trains himself, 'I
  will breathe out steadying the mind.' [12] He trains himself, 'I will
  breathe in releasing the mind.' He trains himself, 'I will breathe out
  releasing the mind.'
  
  "[13] He trains himself, 'I will breathe in focusing on inconstancy.'
  He trains himself, 'I will breathe out focusing on inconstancy.' [14]
  He trains himself, 'I will breathe in focusing on dispassion.'[5] He
  trains himself, 'I will breathe out focusing on dispassion.' [15] He
  trains himself, 'I will breathe in focusing on cessation.' He trains
  himself, 'I will breathe out focusing on cessation.' [16] He trains
  himself, 'I will breathe in focusing on relinquishment.' He trains
  himself, 'I will breathe out focusing on relinquishment.'
  
  "This, Rahula, is how mindfulness of in-&amp;-out breathing is developed &amp;
  pursued so as to be of great fruit, of great benefit.
  
  "When mindfulness of in-&amp;-out breathing is developed &amp; pursued in this
  way, even one's final in-breaths &amp; out-breaths are known as they
  cease, not unknown."[6]


Just as the what was instructed by Buddha to Ven Rahula. This is the only way that i understand and experienced it myself.