Steven:
The relief from stamp duty for first time buyers appears to be such that your wife would be capable of being a FTB, but unless this was going to be your Principal Private Residence, then she would not. You dont say whether you intend trading up or retaining the 2nd property as an investment property.
If it is intended to be PPR, then it should be possible to structure the transaction accordingly. You and your wife can only have ONE PPR as far as I know.
This is from Revenue:
Who is a first time buyer?
A first time buyer is a person, (or, where there is more than one buyer, each of such persons):
who has not on any previous occasion, either individually or jointly, purchased or built on his/her own behalf a house (in Ireland or abroad) and
where the property purchased is occupied by the purchaser, or a person on his behalf, as his/her only or principal place of residence and
where no rent, other than rent under the rent-a-room-scheme, is derived from the property for five years after the date of the current purchase.