When you say that you opened a pension with Irish Life in 1988, I'm assuming that it was a Personal Pension - no employer involvement.
You can't transfer a Personal Pension fund into a scheme, such as the public service superannuation scheme. There's a long way around this, in that you can set up a PRSA, transfer your Personal Pension fund into the PRSA and then transfer the PRSA fund into a scheme. But there would need to be very good reason for you to go to this hassle and expense.
The alternative is to simply leave your Personal Pension where it is in Irish Life and it will continue to be invested until you retire, when you can draw it. Irish Life should be able to locate your policy number by your name and date of birth. No harm updating them with your current address too so that they can send you a statement.
Cheers, Liam