OK first off alot of the rescues are full to bursting at this time of the year. You will find a list of organisations who may be in a position to offer assistance on www.irishanimals.ie
but please note that Kitten Adoption are unable to take in any cats / kittens at the moment.
There are some other cat organisations that are not listed on Irish Animals - try goggling cat rescue dublin.
Pounds only take dogs they do not take cats.
Would suggest ringing your local vets in case the mammy cat belongs to someone in the area & wandered off to have her kittens.
You could try posting on petsireland & irishanimals looking for assistance, but I think that most people who help out with cats & kittens are up to their eyes at the moment but it may still be worth a shot - if you want me to do this for you pm me some contact details & what you want me to post.
The kindest thing to do in the long run if you cannot get any help from any other source, may be to get back in touch with the dspca, who will offer to come & collect them & put them to sleep - it is by no means an ideal answer by anyone's standards, however when faced with the alternative of not having a permanent food source, no vet care, and all of the usual day to day hazards that strayed domestic cats have it may be the kindest. We have all seen recently that there are people out there who get enjoyment from shooting these animals, - a slow painful death from a bullet that doesn't kill outright or being put to sleep humainly.......
Sorry I am not offering more & good luck