In my research into 504s and interactions with our school I found it clear that if we did push for a 504 it would have to be extremely specific. Our teacher and school were very difficult to even speak with about accommodations and in the end we took advantage of the option in our district of partial homeschooling, so that our DS ends up spending very little time with the teacher that was the largest problem. If we'd pushed for a 504 the way we would have gotten things through would have been I believe to have an outside OT look at a detailed copy of his schedule and co-write some specific accommodations that we then showed to the school as a professional's recommendations.
Wording such as, "child will have a reduced writing expectation" is quite vague and in our case would have left far too much thought up to the teacher. A more specific accommodation would be "For journal time, the child will not be required to write more than 10 words".
Even something that sounds clear, such as, "Child will be allowed to use large ruled paper" might be made even more specific by saying, "For spelling tests the teacher will provide the child with 1/2 inch ruled paper at the start of the test".
To make the accommodations so specific and so clear that they can not be misunderstood or changed easily by the teacher, a detailed understanding of the daily schedule and requirements is needed.
I think one can do it gracefully though, emphasizing just wanting to make sure everyone has a chance to have input and feel comfortable with the specifics ahead of time, so that it goes smoothly and so the teacher is not inconvenienced by more meetings.
