This is the tutorial I used to unwrap custom 3D geometry to create UV maps in Blender:
http://wiki.blender.org/index.php/Doc:2.6/Manual/Textures/Mapping/UV/Unwrapping
UV maps can be directly painted on in photoshop to create diffuse (color), specular (reflective), opacity, and bump maps that map very precisely to your object in Keyshot.
You will also need to know how to edit vertices in Blender and some basic photoshop skills (such as working with layers in photoshop). The link I posted links to other tutorials that help with some of the prerequisite skills