Letters of recommendation for Occupational Therapy graduate school?

Is it impossible to get into an average MS in Occupational Therapy program without any letters of recommendation from professors. I have a great letter from the occupational therapist I did over 80 hrs of volunteer time with and two great letters from former employers (one from a mental health facility manager and one from a restaurant owner/chef who I've know for 7+ years) I had a professor who said he'd write me a letter but he's flaking out on me now (which is crap because I busted my a** doing research for him!) Any input is appreciated!