Hello,
Looking at most of raydium object file, they are probably some person who knows how to do that
Have a look at blender tutorial, it's a blender texturing problem and not really related to raydium.To make it short using blender 2.48
Swap to edit mode.
Split you screen.
Open 3d view in one pane, UV image editor in the other one.
Switch to face select mode.
And then the magic key is 'U' to unwrapp your face.
Select an image in the uv editor pane, and fit your face to the right part of the image.
Export using last version of the great export script (or what you have installed it is not a problem).
You can find quite few tutorial about this using google for example:
Blender TexturingHave a nice day
Ouille