How does Dickens tell the story in Chapter 49?
You ask how as if you already know what. But a reference to what is likely necessary before we discuss how.
During this chapter Pip responds to a letter he received from Miss Havisham in which she asked for him to come see her. She wanted to respond to his request to help Herbert. She ends up telling him the truth of Estella's adoption that Jaggers arranged and Pip is convinced that Molly is her birth mother. As a conversation ensues, Miss Havisham prepares a note for Pip to take to Jaggers, and she breaks down about what she has done to Estella, creating the same hatred for men that she has inside her. Miss Havisham had been sitting by the fire when Pip arrived, and as Pip was leaving he turned to see her sitting again by the fire, but instead, she was on fire. It stuck with Pip as he tried to save her that Havisham had asked him to be able to write 'I forgive her' under her name. Pip thought about what that might have meant... especially in relation to Estella.
As to HOW this chapter is told, the voice remains the same, and Pip's entrance to Satis House mirrors his first experiences there. But, the characters abilities have changed. Pip is now in position to help enact a beneficiary scenario for his friend through Havisham, and is the control character. Havisham loses it. Previous experiences together were backwards: Havisham had the control, and Pip's mind was messed with.