I also could speak as ye do: if your soul were in my soul's stead, I could heap up words against you, and shake mine head at you.
If your soul were in my souls stead - if you were in my place, suffering the same adversities.
Heap up words - rather, marshal together an army of words; literally, 'make connection of words' - i:e., arrange them in the order of a set speech.
Shake head - in mockery: it means nodding rather than shaking. Nodding is not with us, so in the East, a gesture of scorn (Isaiah 37:22; Jeremiah 18:16; Matthew 27:39).