This song just gets to me every time I hear it, so I set out tonight to learn it myself.
chords on the version I found here were perfect, but playing solo they were a little
therefore I figured out an easy little finger picking melody that seemed to fit nicely 
playing/singing without a band in the background. So, here goes-

Capo 4 - Chords D2, Am7, C2, G

  D2               Am7               C2               G
e-----0-------0--------0-------0---------3-------3--------3-------3----|
b--3---3-3-3---3-3--1---1-1-1---1--1--3---3-3-3---3-3--3---3-3-3---3-3-|
g---2---2---2---2----0---0---0---0-----0---0---0---0----0---0---0---0--|
d-0--0----0--0--------2-------2---------0-------0--------0-------0-----|
a------------------0-------0---------3-------3-------------------------|
d-----------------------------------------------------3-------3--------|
(Just listen to the rhythm of the song and the pattern won't be hard to pick up)

D2             Am7
Worthy is the, Lamb who was slain
C2             G
Holy, Holy, is He
D2               Am7
Sing a new song, to Him who sits on
C2             G
Heaven's Mercy Seat
[Repeat 2x]

(Chorus- Strum this)
D2
Holy, Holy, Holy
Am7
Is the Lord God Almighty
C2                         G
Who was, and is, and is to come
D2
With all creation I sing:
Am7
Praise to the King of Kings!
C2
You are my everything,
G
And I will adore You


(Verse 2- Fingerpick)
Clothed in rainbows, of living color
Flashes of lightning, rolls of thunder
Blessing and honor, strength and
Glory and power be
To You the Only Wise King,
Yeah

(Chorus- Strum)

(Verse 3- FP)
Filled with wonder,
Awestruck wonder
At the mention of Your Name
Jesus, Your Name is Power
Breath, and Living Water
Such a marvelous mystery

(Chorusx2- Second time with light strumming and end)


Hope you enjoy playing this as much as I do =)
Good Luck and God Bless
-James