It's not possible to export a hook with images. What people usually do when the hook they use requires images is the create a folder named "upload", and then create the folder path leading to the image.
For example:
Create a folder to zip up your IPB hook, and put the .XML file in that folder. Then, in the same folder, create a folder named "upload".
Inside upload, create a folder named public. Inside public, create a folder named style_extra. Inside style_extra, create a folder named your_folder (change it to whatever you want). And then inside your_folder, upload the images you want to use. This also works for javascript files.
And then the code you'd be using is:
<img src="{$this->settings['board_url']}/public/style_extra/your_folder/image.png" alt="" />
Note: You can't use {$this->settings['board_url']} in your CSS, so if you're trying to use it in your CSS, you'll have to either:
A) Use the style_images method instead of style_extra
B) Use inline CSS in your templates, such as this:
<style type="text/css">
.test {
background: url({$this->settings['board_url']}/public/style_extra/your_folder/image.png);
width: 100px;
height: 100px;
}
</style>
<div class="test"></div>
Hope this helps.