I found the one I was looking for. Here it is in case anyone is interested:

A Man Named King
Sung to: "Michael, row your boat ashore"

Once there was a man named King, Hallelujah;
They called him Martin Luther King, Hallelujah
King was wise and he was good, Hallelujah
He believed in brotherhood, Hallelujah
He had a dream for you and me, Hallelujah
He knew that still men must be free, Hallelujah
The freedom road is weary and long, Hallelujah
But Martin sang a freedom song, Hallelujah
We must keep the dream alive, Hallelujah
Freedom's song can never die, Hallelujah
Once there was a man named King Hallelujah
They called him Martin Luther King, Hallelujah