This wouldn't need to be a reasonable adjustment - you'd be welcome to take in anything into the presentation to help you present unless the firm has said otherwise in the instructions.
However, I wouldn't go with a script as you may be reliant on reading it rather than engaging your audience. Instead I would recommend more notes/pointers for what you will say so that your delivery style is slightly more natural rather than scripted.
You can however, take any written documents into a presentation with you to help you present, and if you think a script is better for you, then you should do that. I just tend to find people end up reading from the script too heavily and tend to get less eye contact with their audience than if they used more shorthand/notes.