Last time I was in Kilkenny, there were zones where you could park for free for a max of two hours, then move on otherwise you get a parking ticket, not sure it that was in place throughout Kilkenny, but certainly at the end of Rose Inn st and on John st, which are pretty main thoroughfares. I'd imagine this system would work well for you, it certainly seems to work in Kilkenny, once the two hours are up, you move on, leaving space for other visitors/shoppers etc.
Also worthy of note - Waterford city used to use pay and display parking discs, one disc per hour, so even if you were only stopping for 5 minutes you'd have to pay full whack, however they recently introduced dispensing ticket machines where you can pay corresponding amounts for only 10 minutes, 20 minutes etc, up to a maximum of I think 2 hours, which is a lot more palatable than paying for a full hour when you only need 5 minutes.
Reasons for this may have included resistance from local businesses to supply said discs, so might be worth getting the local chamber of commerce/local businesses to band together if you're not already doing this.