I have to deal with wood-burning smell intrusion, as well: I'm guessing the air intake for my high-eff. HVAC is the source for most of the smoke smell getting in.
We have a very tightly constructed house and I have taken additional steps to prevent smoke infiltration (many of these are an inconvenience), and the smoke still gets in. It behaves like a gas.
1. Applied plastic over the face of our direct vent gas fireplace (it has an air leak I can't identify to fix).
2. Sealed with plastic sheeting and packing tape the grills of each of our 3 bathroom exhaust fans. To use the fan I use a 4 foot step ladder to reach the grill and I pull straight down to open it to the fan servicing position.
3. Sealed the kitchen range vent (in the bottom of the overhead microwave oven) and top side microwave vents using aluminum foil and scotch tape and applied clear caulk at all seams where the cabinets meet the microwave oven. This means we can't use the gas cook stove because it adds carbon dioxide and uses oxygen. So we are using an electric skillet, hot plate, and the microwave oven. About one day a week we are without wood smoke long enough so I can remove the aluminum foil and use the stove.
4. We only use the clothes drier when the smoke level is very low. The drier depressurizes the house and draws air in through the few cracks I can't find.
5. Limit furnace use on nights when an atmospheric inversion is present (we are in a valley, which magnifies the problem). Which are most nights we are not experiencing a due west wind from the wood burners. We have a condensing furnace that draws combustion air from outside, so that prevents bringing in more smoke. The problem is the heat exchangers in the furnace reburn the wood smoke particles because they are in the house air and furnace return air. This makes the most acrid and obnoxious smells and volatile organic compounds imaginable.
6. On Christmas Eve I installed a Honeywell electrostatic precipitator air cleaner in the furnace return just before the fan. I clean and wash it daily.
7. Don't take showers and limit hot water use when outside smoke levels are high. We have a "powervent" natural gas water heater that does not take combustion air from the outside (the fan it has forces exhaust through a pvc pipe out the side of the house), this when it's on, it depressurized the house and will draw in smoke.
8. Applied caulk anywhere I find cracks or openings, such as windows and molding.
And others I can't think of at the moment.
I monitor outside and inside smoke levels (particulate counts) using PurpleAir AQI sensors (laser particulate counters). I can keep the inside 2.5 micron and smaller particulates (the dangerous stuff) very low with the electronic air cleaner, but there is no practical method to remove the volatile organic compounds. Those are what make our life miserable. Since we are bathed in rancid/acrid wood smoke (the poor local woodburner cuts off the air to his stove to control heat output), the stove white smokes all the time and makes really toxic compounds. The VOCs impregnate everything in our house and after a while I can no longer smell them, but bitter things will taste exceptionally bitter and be inedible (grapefruit and coffee for example). That's how I judge how bad the VOCs are.
So, this wood smoke issue has been ruling our lives and I have spent countless hours thinking about it and trying to apply technical solutions to make it through the heating season. Both DW and I are exhausted from it, it's caused lots of anxiety and it's making us ill. That's how bad it is; just about the worst thing that's ever happened to us. This experience prompted me start this thread.