At a minimum I believe that if the income is earned in Ireland and you are resident in Ireland then you are taxable on it here too.
The best thing to do is seek proper tax advise from the professionals about how to optimise your tax situation, rather than getting involved in these kind of grey schemes you have described, as I expect that if you get caught it will cost you a lot more than the 11 percent you are trying to save....
Having spent 20 years contracting here in Switzerland, I can tell you the outcome of a similar scheme that went on here about 5 years ago: When the agency involved was caught, the directors went to jail for 2 years and all the contractors involved were required to pay penalties and interest at 1.5% per month on the outstanding amounts. On top of that, all non EU/Swiss citizens were barred from work permits for a 10 year period and since Swiss permits are linked to EU permits, it means that they are basically excluded from visiting or working in Western Europe for a very long time!
Jim