Upon first reading Luka Rejec's Witchburner, I thought “I want to run this now. And I want to use Burning Wheel. "
Focus on the Situation
Witchburner has analogues to Trouble in Hochen, a Burning Wheel adventure included in Twilight in the Duchy Verdorben.
Below is Trouble in Hochen‘s situation:
You have been sent or called to Hochen. How exactly depends on the nature of your relationship. Hochen is in dire straits—famine in the dead of a hard winter and rumors of infernal influence.
Let's frame the situation for Witchburner:
Calamities beset Saint Cleareyes; Its mayor issued calls for justice. Lord Rightmaker dispatched you to find the witch.
Before you dive into creating characters, read out loud the opening paragraph. Treat it like a movie's opening credits scene. Frame the scene as Lord Rightmaker's initial visit that happened about a week prior.
Depending on your campaign, consider reviewing the gods in Appendix I. This may help players frame their Faith.
The initial offer in the game is 3000 cash. That seems like a lot of cash, but the adventure is implicitly intended for OSR games that reward 1 XP per 1 unit of cash collected.
Consulting both Lamentations and Burning Wheel for references, my first thought was 300 cash equals 1D for resources. From a mechanical standpoint, a 10D offer sounds good.
Looking from the fiction standpoint, it feels a bit much that 300 cash would be 1D of resources. I think of 1D of cash resources as a small purse of silver.
Adjustment: For Witchburner, divide all cash values by 10 to find the number of silver coins. Each 30 silver coins counts as 1D for resources.
Throughout the adventure, Witchburner uses the 5E concept of disadvantage. For example: if you go a day without sleep, you have disadvantage on social activities.
Adjustment: Disadvantage increases the obstacle by 1 (e.g. +1 Ob). Advantage adds 1 dice to the test (e.g. +1D).
Disposition of Villagers
Witchburner provides guidelines on how villagers view the characters. As time passes and the PCs move throughout the village, these dispositions become more important.
The Circles test could be considered a system for determining NPC disposition towards the players. Sure, you find who you're looking for. But what do they think of you?
Leverage the Circles attribute. Since the players are in the village, ignore Place obstacle modifiers. As we already have a time pressure mechanic through tracking watches, ignore Time modifiers. We're not interested in what the villager does, ignore Occupation modifiers.
This leaves Station for setting an obstacle, which seems appropriate to determine their base response.
Adjustment: When characters seek out, or meet a villager, have them roll a Circle test. Set the base obstacle using Station (ignoring occupation, time, and place). The Circle test makes a great Linked test for further interactions. Failure invokes the Enmity clause; Make sure to follow the advice in Witchburner on how to work with this. Adjust the Circle test based on who the villager knows and how the PCs have treated those relations.
To avoid spoilers, I leave those other details as an exercise for the reader.