There's a website about it here, Nickhere:

http://www.knocklong-rescue.com/

And I think this is the poem you're seeking:

http://homepage.eircom.net/~abardubh/poetry/bearla/poem178.html

A little bit of Culture
Posted by Bren Vaughan
December 17 1999
Knocklong
Gabriel Fitzmaurice
Oh, take me through the byroads
To those places named in song
Along the road less travelled
Is the station of Knocklong
Where shots rang out for freedom
In nineteen and nineteen
With young Sean Hogan rescued
By Sean Treacy and Dan Breen.

As I drive to Tipperary
I recall the lore,
The War of Independence -
Here I park my car
On a road become a songline
And walk into the song
The Rescue of Sean Hogan
At the Station of Knocklong.

The station's now deserted,
Blocked up, overgrown
But not the gallous story,
An empire overthrown,
But I am overtaken
By the traffic on the road
Who hoot at this obstruction,
The progress I have slowed.

And so I take the burden
Of History and drive
Into Tipperary
Where I see their Ireland thrive,
But I'm glad I took the byroad
That lead me into song
Many roads to Tipperary
But only one to Knocklong.