I have done it and it can work very well with the right boots. The question of what the right winter boots are is the problem. The best winter boots for this are ultralight mountaineering boots or hikers with a stiff sole. A boot that is meant to work with crampons. Generally winter boots like pac boots are too heavy and bulky and the sole is too flexible to work properly unless you stiffen the boot with a nylon midsole. This is not very hard to do and I will explain the process. In fact the best approach may be to use the ultra cheap pac boots that have a thin sole since they are cheap to experiment with.

You will need a pair of light as possible winter boots two or three sizes over your normal foot size. First you need to find some 1/4 in thick engineering plastic. Nylon works well as will ultra high molecular weight polyethylene. Other plastics will work but it need to be a plastic that is very stiff but slightly flexible and is not super rigid and hard. Acrylics and polycarb will not work well. An even better approach is to make your own custom foot bed from fiberglass and epoxy resin. You will need a little of this anyway for another part.

Take a router or knife and cut out the lugs on a small portion of the sole under the ball of the foot. Only remove enough to make a flat area large enough for mounting and SPD clip. If the remaining lugs on the sole are deep enough you will be able to walk around normally with the SPD clips installed. You need to make a small plate out of fiberglass and epoxy resin so that the SPD clip has a hard surface to be tighened against. You can also use aluminum here but it will make the shoes colder and not as warm. THe original outer sole material is too soft for the SPD clip and binding interface and will not transfer force properly. So you need this small hard surface under the SPD clip. Then you put your stiffening midsoles inside the boot and drill holes all the way through the sole and through the custom midsole. You will need to then counter sink the holes in the midsole and use a flat head cone shaped bolt so that you have as little bolt head sticking above the midsole surface as possible. T nuts also work well and better in some cases.

Then you just put a little silicone glue on the outer SPD plate and tighten the hole thing together. You may have to put a small amount of padding over the midsole to cushion the bolt heads. Generally the thick felt boot liner is sufficient if you have the bolts countersunk enough.

This method works best if you start out with a lightweight boot to begin with. And the more layers of foam that the sole of the shoe has the warmer it will be. The right sole is the most important part of having a warm shoe since the rest of the foot can be easily insulated with wool socks if the boots are not too tight fitting.