sketchup texture

I have imported a sketchup model and some of the textures are wrong
Is there an easy fix?
Basically there are many textures compiled onto a few large images
How can I apply part of an image as a texture? it does do some correctly but i dont know how it maps part of an image to an object
I was thinking UV but how do I make blender use only part of the image for the texture, it wants to use the entire image