Creating custom ImageCache actions...

You need to look at imagecache.module as an example.

You need to implement hook_imagecache_actions in your module.

The action data is cached so you should make sure you have the following in your install file..

<?php

function hook_enable() {
  cache_clear_all('imagecache_actions', 'cache');
}

function hook_disable() {
  cache_clear_all('imagecache_actions', 'cache');
}

?>