We had a similar situation dealing with disclosure of employees names to
researchers.  The researcher wanted names of all employees so he could
send a letter to them about his research.  We felt like it was inappropriate,
so we got the cooperation of the Director of Human Resources.  That dept.
send out letters to employees telling them very briefly about the research.
and included the name of the individual to contact in the event they were
interested in participating.  Interested employees returned a post card with
contact info. or called and gave their phone number.

I suggest you get the cooperation of your Director of Disabled persons and
use a similar method.  I'll send you the wording of the initial contact
letter if your interested.

Rebecca Bacon
Eastern Virginia Medical School
xxxxxx@picard.evms.edu