Does anyone have experience with helping an otherwise very bright and capable student conquer writing hang ups?

We have come a long loooonnnnnggggg way in understanding and helping my DD18 since I started searching for answers last year, my DD has matured exponentially, has hope, is no longer depressed and is responding extremely well to the ADD meds...

HOWEVER, there still seems to be some kind of major hang up about writing. I don't get it, she can write, and has written some really good creative stuff, but only on her terms and her schedule. Whenever I suggest a writing assignment the reaction is pure terror, physical shaking, tears, begging...catatonic shutdown. I went back and reviewed some of my posts from before we got the evaluation and diagnosis of ADD and ASD and I came across this article on NVLDs which may shed some light but it does not offer any concrete suggestions for dealing with/overcoming the difficulty:

http://www.ldonline.org/article/6114

Time is getting short as she will go off to college in late August and there will be quite a few writing assignments...I want to make sure she gets off to the best start possible. With a DX of NVLD instead of or in addition to ASD/ADD would there be justification for asking for special consideration on writing assignments like reduced length expectations, heavier weight on oral interviews or??? Or better yet, is there a way to help someone overcome this type of paralyzing writing phobia?