Sampling a floating point texture where the alpha channel holds 4-bytes of packed data into the float. I don't know how to cast the raw memory to treat it as an integer so I can perform bit-shifting operations.

int rgbValue = int(textureSample.w);//4 bytes of data packed as color
// algorithm might not be correct and endianness might need switching.
vec3 extractedData = vec3(  rgbValue & 0xFF000000,  (rgbValue << 8) & 0xFF000000, (rgbValue << 16) & 0xFF000000);
extractedData /= 255.0f;

GLSL? floatBitsToInt / intBitsToFloat

That's it, thanks.