Ever since I saw Brooke playing this live and noticed that she was playing it 
differently to what I had learned it bothered me, and one day (I can't remember 
how, I think I was just browsing Youtube) I found this video of a guy who showed 
how to play it like she does. The E used (I looked this up to check the actual 
name of the chords) isn't the same as the one I found which was pretty much an Em 
with the e, B and G strings blocked, and technically it is just another way of 
playing E as it uses the same notes, but it's played like a power chord would 
usually be played. I wasn't sure about the G#5 or the F#5 so I just wrote them as 
fifths since power chords seem to have a habit of that.
So here it is, Hosanna in power chords. Thanks to Jon Fletcher (who I learned it from) :]

Chords used:
C#5:e 0  E: e 0  A5: e 0  B5: e 0  G#5: e 0  F#5 e 0
    B 0     B 0      B 0      B 0       B 0      B 0
    G 6     G 9      G 3      G 4       G 4      G 2
    D 6     D 9      D 2      D 4       D 6      D 4
    A 4     A 7      A 0      A 2       A 6      A 4
    E 0     E 0      E 0      E 0       E 0      E 0


Intro: C#5  E  F#5  Ab5 x2

[Verse one:]
E
I see the king of glory
C#5
Coming on the clouds with fire
                 A5                       B5     C#5  
The whole earth shakes, the whole earth shakes
E
I see his love and mercy
C#5
Washing over all our sin
            A5               B5
The people sing, the people sing


[Chorus:]
C#5 A5    B5 C#5
Hosanna, hosanna
    A5         C#5 B5
Hosanna in the highest
C#5 A5    B5 C#5
Hosanna, hosanna
    A5         B5  C#5
Hosanna in the highest


[Verse two:]
E
I see a generation
C#5
Rising up to take the place
               A5                   B5
With selfless faith, with selfless faith
E
I see a new revival
C#5
Stirring as we pray and seek
              A5                 B5
We're on our knees, we're on our knees

[Chorus:]
C#5 A5    B5 C#5
Hosanna, hosanna
    A5         C#5 B5
Hosanna in the highest
C#5 A5    B5 C#5
Hosanna, hosanna
    A5         B5  C#5  E  F#5  Ab5
Hosanna in the highest

C#5  E  F#5  Ab5

[Bridge:]
A5                         B5
Heal my heart and make it clean
E                       C#5
Open up my eyes to the things unseen
A5                       B5                 C#5
Show me how to love like you have loved me
A5                              B5
Break my heart for what breaks yours
E                         C#5
Everything I am for your kingdom's cause
A5                   B5    C#5
As I walk from earth into eternity


[Chorus:]
C#5 A5    B5 C#5
Hosanna, hosanna
    A5         C#5 B5
Hosanna in the highest
C#5 A5    B5 C#5
Hosanna, hosanna
    A5         B5   C#5
Hosanna in the highest
    A5         B5  E
Hosanna in the highest