I’ll just leave this here: http://www.burningwheel.org/forum/showthread.php?14092-Hack-Townies-Life-in-the-Rut 
Basically it allows for a slightly more BW experience by leaving space for play outside of dungeons and adding an extra “Belief” that I call your “Agenda” which should allow for more internal and external cross-purposes.
But, maybe you want a deeper BW experience, so lets break down the biggest differences…
Turns, Checks, Light, and Gear
These are straight up mechanics that just don’t exist in BW and don’t have equivalents really, turn them on when you need them, turn them off when you don’t. Leaving for an adventure site? Fill out the equipment sheet and then start the adventure phase. Just got back to town from an adventure? Either switch to BW immediately or, better yet, go through the TB Town wind down and then shut off the TB tap. This part doesn’t seem super complicated.
Conditions
I’m a little rusty with my BW, but from what I remember they basically just have a scale for the Injured condition. The way I see it? Use the TB conditions all the time! If you happen to be in a BW Fight! for some reason, use the BW Physical Tolerances and then at the end of the fight give each player a single condition based on how injured they are:
Su -> Hungry and Thirsty
Li -> Exhausted
Mo+ -> Injured
Conflicts
I say mix and match, why not? If there’s a reason that doesn’t occur to me now, then let me know, but I don’t see why you couldn’t use TB conflicts for all the minions and minor encounters for the simplicity and then switch to a BW Fight! for the final boss battle. Sounds epic! The only thing to keep in mind is that conflicts are not optional in TB, they are an integral part of the game, so if you are mixing and matching don’t assume that means you can use a bloody versus. If you do your players will likely find themselves with too few checks and not enough advancement.
Rewards
I could go either way with this one, I’d say pick the reward set that you like best and stick with it. You can still track class advancement by how you use them either way, though the rate of advancement might not be optimized for BW play. This is something to experiment with. (Note: if you are using BW style wises, you may want to divorce the reroll options from your wises, though you certainly don’t have to)
Skills
BW has more and a finer grain of them. imho this is because TB wants the focus on describe to live instead of personal story, it is your actions that matter more than your personal story. Also, the GM has more control over interpreting which skill is being used based on your descriptions, and a simpler skill set makes that easier. The simplest option is to just use TB skills, but you lose the fine grain of character. The more complex option is to just use BW skills, but this will make the GM’s job much more difficult and likely result in a lot more beginner’s luck roles. There are two slightly more complex options.
Switch. When you start adventuring translate from BW skills to TB skills. This is a little weird because a character with Sleight of Hand would probably get Criminal and now be able to pick locks, a skill they didn’t have before. It also requires a fairly extension conversion chart or at least a lot of discussion.
Hybrid/Negotiation. The players can keep their BW skills when they adventure but the GM thinks and factors using the TB skills during the adventure phase. When the players describe doing something that involves risk then the GM calls for a TB skill and obstacle. The player then suggests a BW skill that seems appropriate, if the GM accepts then the player rolls that skill. If the GM rejects then the player rolls beginners luck for a different skill of the GM’s choice. It’s a little less smooth as compared to TB raw, but I think it might work.
To me Skills are the hardest part, so you could try different things out and go with whatever seems to work best for your group.
Attributes and Stats
If you’re already burning up BW characters, I say just use the BW Stats. It shouldn’t be too hard to figure out which stat goes with which TB skill. I suspect that TB Abilities are simpler than BW Stats for the same reason that the skills are simpler, to keep things simple and draw the focus toward describe to live. However, if you’re already used to BW then I don’t think have 6 rather than 2 core stats will make a huge difference.
You could also just average your BW physical stats to get your Health and mental stats to get your Will, but then how does advancement work when you switch back to BW stuff?
Nature
Doesn’t exist in BW, so just use it as written from TB.
Resources and Circles
You don’t use Resources or Circles in a dungeon anyway, so go with BW.
Magic
Tough… it would be hard to switch back and forth… I could see either working and would personally lean toward just using TB magic for the most part. However, if you use BW magic, don’t forget that casting a spell does not consume a turn.
Summary
Did I miss anything? Almost certainly! But it’s a start. However, it seems doable, albeit nowhere near as clean as just sticking with a system built for a specific purpose. However, if you plan on doing an entire campaign of just adventuring and then use the same characters for another entirely separate campaign of BW shenanigans (or vica versa) then yeah, it would be easier and smoother just to burn a new character for the second campaign with similar stats and skills, and just slap the same name on it.
