I would write a letter to their HR department including all info:benefits, prices, set up e.t.c as they will probably be the ones to decide. I would call up the companys to ask for the name of the head of HR or if they don't have a specific department ask who would be best to write to, as when you write to a specific person you are more likely to get a response. This would work better than cold calling as they have a chance to think it over. I know some offices have an onsite therapist with a specific treatment room, you could explain that you could use a conference room for so many hours a week/month. I would be very specific about the details as it will help them to see how it would be possible to accomodate you.