You don't say the age of the students nor whether they have learnt to read and write in their mother tongue. Also, do these students want to read and write in English or do they want to focus on spoken language? A discussion of these aspects with the students or parents would be a good place to start.
It's important to coordinate or at least try to speak to his / her regular teacher to see what methods are being used. This teacher would also be able to tell you the degree of dyslexia and what you can expect to achieve. The students might know the answer, so talk openly about it. People with learning difficulties understand their own needs and are an obvious source of information. The parents probably have insights too.
People with dyslexia often have problems with sounds in the language. This is especially difficult in EFL as English is not a transparent language - there isn't an obvious relationship between the sounds and the written word. You need to consider this and adapt your expectations accordingly. In teaching dyslexic children to read in their mother tongue, work on rhymes and alliteration has been proved to be beneficial.
I don't know of any materials written for people with dyslexia who are learning a foreign language. Multi-sensory teaching has been used when introducing new words in the mother tongue. For this, children are encouraged to use all their senses. For example, a new word is presented visually (ie in its written form), the child looks at it, listens to its sound at the same time, repeats it and traces the feel of it on wooden letters.
If you want to read more about this, you can look at C Hulme (1981) "Reading Retardation and Multi-sensory Teaching" published by Routledge and Kegan Paul.