Even if the song is sung acapella, the chords fit in quite nicely.
You can also try singing the actual bass notes onto the song.
(same chords for every verse)

C                     G                    G                   C
If you miss me at the back of the bus, and you can't find me nowhere 
F                   C                 G                    C
Come on over to the front of the bus, I'll be ridin' right there 
C                    G
I'll be ridin' right there 
G                    C
I'll be ridin' right there 
           F                   C  
You got to come on over to the front of the bus 
G                    C
I'll be ridin' right there 

C                     G                  G                   C
If you miss me at the cotton fields, and you can't find me nowhere 
F                    C          G                     C
Come on down, to the jailhouse, I'll be roomin' right there 
C                     G
I'll be roomin' right there 
G                     C
I'll be roomin' right there 
F                   C
Come on down to the jailhouse 
G                     C
I'll be roomin' right there 

C                     G                      G                   C
If you miss me in the Mississippi River, and you can't find me nowhere
F                   C           G                    C
Come on over to the city' pool, I'll be bathin' right there 
C                     G
I'll be bathin' right there 
G                     C
I'll be bathin' right there 
F                   C
Come on over to the city' pool 
G                     C
I'll be bathin' right there 

C                     G                 G                 C
If you miss me at the picket lines, and you can't find me nowhere 
F                         C      G                    C
Come on down to the court house, I'll be votin' right there 
C                    G
I'll be votin' right there 
G                    C
I'll be votin' right there 
F                   C
Come on down to the courthouse 
G                    C
I'll be votin' right there 

[Verse 1 again]