I found a good article that discusses modifying achievement test items so that they more fairly assess what students with disabilities know.
It can be found through the database: Academic Search Premier. Here is the information.
Title: Modifying Achievement Test Items: A Theory-Guided and Data-Based Approach for Better Measurement of What Students With Disabilities Know.
Authors: Ryan J. Kettler, Stephen N. Elliott, and Peter A. Beddow
From the Peabody Journal of Education, 84: 529-551, 2009.
The ideas in this article could be used when modifying any type of test for students with disabilities and I found the ideas to be very useful. Hopefully, they can help you too!