The first modern linguistic analysis of a signed language was published in 1960 by William C. Stokoe, Jr., a professor of English at Gallaudet University, Washington DC, the only college for the deaf in the world. Nearly sixty years on, research in the area of sign language linguistics has established that signed languages are fully developed natural languages with their own syntax, morphology and phonology. The morphology and phonology of signed languages is concerned among with manual and non-manual features. These include handshapes, head, torso, eyebrow, eye, cheek, mouth, nose, chin and tongue movement and also movement of the shoulders. On application of various phonological rules these are used to represent the morphemes, phonemes, phonomorphememes and lexemes of Sign Language. This paper is concerned with determining the computational lexicon morphological-phonological interface of Irish Sign Language Sign (ISL) for sign realisation. We provide an outline of our proposed computational phonological parameters for ISL. These parameters are determined with a view to developing a lexicon architecture that is capable of representing the linguistic phenomena consistent with Sign Language and in particular to this research, ISL.