Yes, in a nutshell - using "standard" E A D G B E tuning, try this -
1. learn the notes of the neck and learn to make your own chords
   without using all of the strings of the guitar in your chord.
   For example, you may use the bottom three strings, or the top
   three, or two or three in the middle and let the others rest.   
2. Find a shape, ie, the shape of Am7, or Em and simply move it up
   and down the neck and see where it works and where it doesn't.
   You may also add another string/note "wherever," to see how that
   sounds with your "shape" in any specific position you desire.
3. The key for playing Irish music using a guitar in "standard"
   tuning is: get away from "standard" chords as an "all the time
   thing;" drop the third out of the chord; and, find a drone note
   to use with the chord whenever you can.

Now, before I have a horde of "monster" guitar players come on here and fill this thread up with statements to the effect that I don't know what I'm talking about - let me say - they're right. I am not
a guitarist - I play the instrument the best I can using it as a vehicle for my voice and the songs I present while making my living. What I have given you at the top of this write is a small bit that came out of four, two-hour, sequential group classes titled, "Guitar -Irish Music In Standard Tuning" that I attended at the O'Flaherty Irish Music Retreat in Midlothian, Texas back in October of 2006.
The class was taught by Matt Heaton (he plays with many of Irish music's "biggies") and he has a website somewhere on the internet -
find it and contact him and I'd bet he'd give you a tip or two.
You may also want to look up O'Flaherty's Irish Music Retreat as
well - three days of total immersion in Irish music - all Irish instruments and voice. Hope this helps. Cheers.