You probably could as wood boilers excel at high heat which is required to flash water into steam, but the reality is, I am not sure you would ever want too. Doing so takes a high amount of BTU's and that is just not efficient.
If you were going to make a conversion you would be farther ahead to convert a radiant floor heating system. There are many ways to do that, and on any type of flooring situation, from retrofitting existing concrete slabs to old wooden floors. Since you are heating the items in the room, and the occupants themselves, and not the air, you get the same benefits as steam heat but without the cost.
The cost of steam is really staggering, you are taking water at ground temperature and trying to heat it to 220 degrees plus. That is a 162 degree rise in temperature in a very short amount of time. In contrast, radiant floor heat uses very little water temperature because it uses what is already in the room to act as a heat sink. In this way you are heating the water from ground temperature to a mere 86-90 degree temperature. That is only a 32 degree rise in temperature.
Of course that is from a cold start, but even assuming the condensate coming back to the boiler is a 180 degrees, you still have a 40 degree rise that your boiler must compensate for, where as with a radiant floor heating system, the returning water is only a 15 degree drop. By those comparisons alone you are taking 60% better efficiency with a radiant floor heating system.
Adding a wood heating unit only adds to the efficiency.A neighbor uses and inside wood heater to heat a 275 gallon drum of water, but since his radiant floor heating system draws such little heat off that tank, he only has to fire up his wood heater every few days. Since the average heating season here is 150 days, even if he has to start a fire every other day and let it go out, he is only using half as much wood as he would by letting it burn 24/7/150.
There is way more to all this then what I am explaining, but with those simple figures it is very easy to see that with efficiencies like that, the return on investment, or pay back, on converting from steam to radiant floor is so vast that it makes the conversion well worth your time and effort.
I agree with you, forced hot air heating sucks, but there is a way to get all the benefits of steam (and even more benefits besides) without the high cost.