Elysium is as far as to
The very nearest Room
If in that Room a Friend await
Felicity or Doom--
What fortitude the Soul contains
That it can so endure
The accent of a coming Foot--
The opening of a Door--
By characterizing the sound of a footstep as an “accent” Dickinson  personifies  it. An accent is “a distinct emphasis given to a syllable or word in speech by stress or pitch” (Collins Concise Dictionary): consequently, the foot step becomes a unique sound, almost taking a life of its own. In the context of this poem, one could suggest it is God or a greater force coming to claim a life.
Elysium is as far as to