Method for including bacon in an otherwise vegan chili?
You have two different approaches from Catija and eckes, depending on what you favor, but you could also combine both approaches - 

Start by chopping up the bacon, and then cooking it in the pot until it's nicely crisped and the fat is rendered.

Remove the bacon with a slotted spoon, to paper towels to soak the remaining fat from the bacon and leave it in it's crisped state.  Leave the drippings/fat behind in the pot, and use that instead of oil to saute the vegetables.  This will allow the bacon flavor to permeate the dish, overall, a bit more.

Then, either just before serving, or on the side to sprinkle over the served dish, add the bacon or allow the eater to add, themselves.