Hi Angela
I have good news and bad news!
The bad news is that in my experience, assistive technology is very personal and related to individual needs. I don't think it would be possible to specify your assistive technology needs in advance.
The good news is that you can and should specify your accessibility needs in advance, particularly when tendering for software. The NDA's IT Procurement Toolkit will help you to ensure that the goods or services you procure will be accessible to the widest possible audience - see
http://universaldesign.ie/useandapply/ict/itprocurementtoolkitThe 'Web Technologies' section of the toolkit includes standard texts that you can cut/paste into your tender document to ensure that any web services you procure comply with the WAI WCAG 2.0 guidelines for web accessibility.
Hope this helps, and feel free to repost with further queries.
Shane