Do you mean you're not sure how to broach the subject with an interviewer?
As you've already got through to the final round of interview with a number of agencies, they must see something they like in you and your work and mentioning that you're dyslexic at this point shouldn't cause an issue. If you don't say anything, an employer will eventually notice you're struggling with certain tasks and feel the need to take action which will possibly come in the form of a "you've got lazy, pull your finger out" speech (really useful when you can't do anything about it!!). If you do disclose your dyslexia, your new employer will likely be more understanding of your situation and can help you work around things you find difficult. You may even be surprised to learn that you're not the only dyslexic in the company!
So, in answer to your question, I feel that you should discuss your dyslexia with prospective employers but rather than building it up in your head as a massive deal, make light of the situation maybe even crack a joke about it! At the end of the day, you're quite comfortable with your lot in life and by showing this in a high pressure situation such as an interview you'll put the interviewer at ease about it.
Best of luck in your interviews, I'm sure you'll do really well.
Hello, I'm dyslexic too I make some cracking typos, misinterpret things and generally have "Dohhhhhhhh" moments when I realize I have taken something completley the wrong way. My advice is be honest and up front about it. Yep you'll need to spell check and re-spell check your work but as long as potential bosses know about it they should be supportive. Mine all have been