How? Here's how:
We follow a few simple instructions laid out for us in detail, for:
Step 3, and Step 4, in the Big Book.
Then, as a result of following that process... it changes our perceptions.
Once our perceptions have been changed -- the resentments are gone.
What's actually happening is, what Bill W. wrote about further on in the Big Book (after he gave the instructions for Steps 4 & 5) where he wrote something similar to: "to get over drinking requires a transformation of thought and attitude."
Bill had an interesting way of writing. He would give us some instructions to follow; then we would suspend our judgements long enough about the instructions to take the actions; taking the actions would produce results; then, later on... Bill would explain something that would explain what the principle was -- that produced the result.
So... by applying that here's what I come up with:
1. "to get over drinking requires a transformation of thought and attitude."
Ok... How do I get over a resentment?
2. "to get over RESENTMENT requires a transformation of thought and attitude."
See how it works?
You might then ask: Why didn't Bill just tell us that in the first place?
We... I don't think Bill consciously knew that he was doing it that way. Maybe he did and maybe he didn't.
Either way -- my experience has shown that IF an alcoholic is told about "how to get something" without "giving instructions for actions to take" then he/she won't take the actions... and thus, won't experience the experience.