If 4 steps are the only impediment to the entire building being wheelchair friendly, perhaps those four steps could be replaced by a permanent ramp? If the steps are wide enough, perhaps one side could be a permanent ramp and the other side remain steps. I would be putting it to the OC that this might be a good thing for the building in the long term, not just a benefit for the particular residents that need it just now.
As an OC cost spread among all owners it should not cost too much. For those who think they would never use it, perhaps they can be consoled by the idea that the value of their unit would rise.
I suggest doing the work for the EC. Find out what a good permanent solution would cost, talk to neighbours about it, then put a proposal to the next general meeting. If a general meeting votes to install, the EC has to do it.