Generally rural housing policy is designed to accommodate only 'rural generated housing need', which includes people who are an intrinsic part of the rural community, persons working full-time or part-time in rural areas, returning emigrants to rural areas and individuals with exceptional health circumstances who are required to live in a particular rural environment or close to family support. This is what is recommended in the Sustainable Rural Housing: Guidelines for Planning Authorities.
Why don't you download the local needs application form from Wicklow County Council's website (planning section) to find out the exact documentation that you would be required to submit with a planning application to prove the above (or their specific requirements). That should let you know straight away whether you qualify or not.
Also, you need to look up Wicklow's precise rural housing policy which will be detailed in county development plan and which may vary from area to area within the county.
Most local authorities are clamping down on one-off rural housing that is not for local needs, especially in areas within commuting distance of Dublin, as development in many areas is unsustainable and growing beyond that at which the necessary infrastructure, services and amenities can be provided to support the population.
From what you say if you live in South Dublin (although you don't say where) and are not from a rural community in County Wicklow or do not work in a rural area of County Wicklow then your chances are slim. But do look at the local needs form and development plan to see exactly what is required.