Because of the general lack of parking spaces and the high number of people who may need them, my first thought is to wonder whether this may also be a building code violation.
That said, you have a sticky wicket because of the general lack of parking, etc.
I'd start by sending a letter to the management, by certified, return-receipt mail (about $5.50) asking that you be alloted two handicapped spaces because there are two people who need them. Ask them to get back to you no later than 5:00 pm on November X, 2010 (give them a couple of weeks if you can). If nothing else, you have now established a paper trail. (I realize that you may have already done this, but wanted to start here, just in case).
If that fails, I'd file a housing discrimination complaint.
If there are enough employees, you have the right to file a complaint with both the state discrimination agency and the federal one, the Equal Employment Opportunity Commission (EEOC).
In New York, you can contact the state agency here: http://www.dhr.state.ny.us/faqs.html
If you start with the state agency, in most states they'll file a complaint with the federal agency, HUD, on your behalf at the same time.
There are deadlines for filing, so don't delay!
Complaint investigations are free. They're not always the best, XXXXX XXXXX do get a free investigation. If it looks like they are going to file a "no cause" finding, withdraw your complaint before they do. That way, if you go to court, a "no cause" finding can't be used against you.
The third and final option is, of course, to hire an attorney to sue. However, this could cost you a lot of money, including paying fees and costs for the "other side" if you lose. In addition, it will cost your association a lot of money in attorney fees, which will hurt your along with everyone else.
If you have any follow-up questions, please write back. I'm through for the evening, and will check back in the morning.
Otherwise, if I've answered your question, please click on "accept" or I won't be paid.