Hmmmm! When I was involved in teaching painting summer-schools in Ireland myself and my co-teacher (who was then Artist in Residence in the National Portrait Gallery in London) did a month in early September, after most of the tourists had gone home preparatory to the start of the new school term (we have a 3-term school and college year here, very different to your semesters in the USA). The big thing about the western seaboard is to work outside from nature, which is very spectacular.
It is unlikely you will find any fine art (sculpture, painting or drawing) workshops/weekends this close to Christmas, given the vagaries of the weather etc. (it was -4 here in Essex UK last night!)
However..........as an artist and past teacher I always feel people underestimate their own innate talents and perceptions and if you want to get some very special, personal, memories of your visit to Ireland get yourself a good-quality water-colour block, a couple of tin boxes of watercolour paints and 6 graded 'H' pencils (most usefully HB, H2, H3, H4, H5, H6) and get yourself a spot on some cliff-top out of the wind so you won't be blown out to sea.........then let what happens happen, and let us know how you get on!