Both of the following shaders can be found in my Shadertoy.com adaptions
Boxmapping.fsh
Cheap Cubemap.fsh
where they are in the Shaders = ShaderToy\Shaders\Inigo Quilez folder.
Both map a texture onto a sphere and a plane but it is trivial to remove the plane. In both cases there is a section of the code introduced by the comment
// raytrace-plane
and a line or two later there is an "if" statement
if( h>0.0 )
A minimal edit to disable this is to change it to
if( false && h>0.0 )
I have tested it and it works a treat.
Or you could just delete the if and the code that depends on it. Do not delete the declaration of h just above the if because it is used by the code projecting the texture on to the sphere,
If you do not already have them the Shadertoy adaptions (without this little mod) can be downloaded using the direct link
http://www.theemusnest.eu/scenes/Zips/ShaderToy%20Scenes/ShaderToy.zip