I came across an old out-of-copyright edition of the Christian Brothers' Irish Grammar (from 1902), and thought that the opening chapter on pronunciation would do well as the basis for a general introduction to Irish lessons on Celtic-L.
As source material for these lessons I'm using Teach Yourself Irish, Buntus Cainte, New Irish Grammar by the Christian Brothers, and a book on Ulster Irish called "The Irish of Tory Island". So if you see sentences or examples that come from these books, it's not a coincidence.
Armed with the pronunciation guide we can start the grammar. I won't give any more pronunciation to words because I don't think mine would be reliable anyway; after doing the lessons you can move on to tapes or download some online sound-files in Irish. These lessons are cobbled together using information and examples gleaned from a number of different Irish textbooks, so if you hear anything that sounds familiar that's why. Corrections to any of this material from Irish-speakers on the list are always welcome -- I'm neither a native-speaker or even an advanced learner and make no claims to infallibility; I summarize grammar well and that's about it.