Your plans for starting a theater group for children with Dyslexia sounds wonderful. I don't have any direct experience with starting a program like that, but I do have some thoughts as to who how you may gain additional information to pursue your dream.
 
Lindamood-Bell http://www.lindamoodbell.com/ provides excellent, evidence-based training and guidance on supporting children with learning disabilities. I have always been impressed with their strategies, and I believe that they help children greatly with language. Their strategies are more consistent with a typical "tutoring" paradigm, but you should consider call them and talking with them about your plans.
 
Also, if you would like to get in touch with a school that has excelled in supporting children with learning disabilities, I would recommend that you call Charles Armstrong School in California http://www.charlesarmstrong.org/. I know that you are in Michigan and likely can't visit, but I cannot recommend the school enough. The focus of the school is to help children with learning disabilities, and they are very, very good at it. I have seen shy, timid, struggling students convert into confident, smiling students with good academic skills after a year or two at Charles Armstrong. Perhaps, they have some ideas on how you might start your program.
 
Don't give up on your dream! Good luck!
 
L. Compian, Ph.D.
Counseling Psychologist
Education.com

This is a great time to be pursuing a career working with dyslexic children. There is a lot more advanced and concrete research on the subject and a host of excellent organizations that work to help dyslexic students. The idea of mixing academics with movement sounds wonderful.
 
I would recommend doing a lot of research on organizations that do research-based work with dyslexics to learn what schools or programs they recommend for training and it can help you decide what type of training you feel you need to be successful. It may also help you decide how to structure your program and whether partnerships with some of these organizations, might be in your future.
 
Here is a link to the International Dyslexic Association, which does have a branch in Michigan.
 
http://www.interdys.org/Branchdetail.aspx?bid=27
 
Here is a link for the Masonic Learning Centers for Children. They began a partnership with Massachussetts General Hospital in 1994 to help dyslexics and I have a friend who has worked in one of their New Jersey learning centers and raves about the program. They do have 3 learning centers in Michigan.
 
http://www.childrenslearningcenters.org/home.html - Masonic Learning Center homepage
 
http://www.childrenslearningcenters.org/about/mi.html - Masonic Learning Center, Michigan branch information
 
I would also recommend looking over the Bright Solutions site. It was started by a woman who was passionate about helping her dyslexic nephew. Her methods are based on the Orton-Gillingham approach.
 
http://www.dys-add.com/teach.html
 
Here is a site depicting the history of the Orton Gillingham approach.
http://en.wikipedia.org/wiki/Orton-Gillingham
 
Here is one more sight to review.
http://www.orton-gillingham.com/index.aspx
  
I wish you the best with this endeavor!
 
Best regards,
Lori

I think theater is a wonderful way to help dyslexics with learning how to read.  It is a very fun, hands-on, multisensory learning system.  What a fantastic idea!  Also you will find that a lot of dyslexics have a gift in acting, drama, dance, etc.  It should give them a great boost of confidence and something nice to look forward to.  As for the training.  It is a lot of work to become trained as a teacher for dyslexics but well worth the time and investment.  You will first want to look into getting a teaching credential in Special Education.  Then you can specialize in a reading program such as Orton-Gillingham and receive a certification in that.  I do believe that there are training programs for Orton-Gillingham in Michigan.  You would go through the training program and then do a supervised internship. You can also check out the Academy of Orton-Gillingham.   Orton-Gillingham is the best program for struggling readers and students with dyslexia.  After you become trained in O-G, you can figure out how to combine it with your theater program.  I wish you so much luck, it sounds like a fantastic idea.