A simple solution is to use POV-Ray. Create a file like
camera
{
spherical
location <0, 0, 0>
}
box
{
<0, 0, 0>, <1, 1, 1>
texture { pigment { image_map { bmp "w4.bmp" } } finish { ambient 1.0 } }
translate <-0.5, -0.5, -1.5> rotate <0, 0, 0>
}
box
{
<0, 0, 0>, <1, 1, 1>
texture { pigment { image_map { bmp "w3.bmp" } } finish { ambient 1.0 } }
translate <-0.5, -0.5, -1.5> rotate <0, 90, 0>
}
box
{
<0, 0, 0>, <1, 1, 1>
texture { pigment { image_map { bmp "w2.bmp" } } finish { ambient 1.0 } }
translate <-0.5, -0.5, -1.5> rotate <0, 180, 0>
}
box
{
<0, 0, 0>, <1, 1, 1>
texture { pigment { image_map { bmp "w1.bmp" } } finish { ambient 1.0 } }
translate <-0.5, -0.5, -1.5> rotate <0, 270, 0>
}
box
{
<0, 0, 0>, <1, 1, 1>
texture { pigment { image_map { bmp "w5.bmp" } } finish { ambient 1.0 } }
translate <-0.5, -0.5, -1.5> rotate < 90, 90, 0>
}
box
{
<0, 0, 0>, <1, 1, 1>
texture { pigment { image_map { bmp "w0.bmp" } } finish { ambient 1.0 } }
translate <-0.5, -0.5, -1.5> rotate <270, 90, 0>
}
The images w1, w2, w3 and w4 are the "normal" views, w5 is the view up and w0 down. It may be that the images must be reordered or the rotation changed, depending on how the images have been generated.
The current beta has HDRI-support, just change the filetype to hdr.