I have an American/Canadian Chase Visa, can I waive CDW?

Yes, you can as long as you meet the CDW terms:

You must hold either a US issued World MasterCard or Canadian issued Gold/Platinum Visa and provide WRITTEN PROOF that the card has relevant coverage for THE REPUBLIC OF IRELAND. This letter must be dated no more than 2 weeks prior to arrival. If a relevant card and cover letter are not produced at the time of commencement of rental OR you have chosen an exclusive rate, and do not hold a credit card that will cover you for CDW, you will be charged for CDW on arrival at the local daily rate.