If the files are in the same directories, it should just work. E.g. if you have an OEBPS/Images directory containing img1.jpg, and an OEBPS/Text directory containing HTML, and the HTML has an image tag like this:
Code:
<img src="../Images/img1.jpg"/>
it should work fine as long as you have the same directory structure in the new book with an Images and a Text directory. If not, replace "../Images/" with the correct relative path from the HTML directory to the images directory -- or, of course, remove it completely if the HTML and images are in the same directory.
Himt: hover the mouse over a filename in the editor's File Browser panel, and the full path is displayed at the bottom left of the window. Just in case you didn't know, a relative path like "../Images" means "go up one directory level" (from OEBPS/Text to OEBPS) "and then down into Images" (so now you'll be in OEBPS/Images).