OK, tested and it works a treat. For anyone else following this thread, the process is;
1. Create in the root plugins folder a new folder called `tiny_mce`
2. Inside the new tiny_mce folder create a new folder called `config`
3. Go to `zp-core\zp-extensions\tiny_mce\config` and copy any or all of the existing config files to get you started.
4. Place the copied files in your new `\plugins\tiny_mce\config\` folder
5. Rename your copied config file(s) to something unique for each file, e.g. add a prefix like `my` or anything else you wish to use.
6. Open the new renamed config file and ensure the first javascript line is pointing to the correct location of the normal tiny_mce.js file, by default this should be
`<script language="javascript" type="text/javascript" src="<?php echo WEBPATH ."/" . ZENFOLDER .'/'. PLUGIN_FOLDER; ?>/tiny_mce/tiny_mce.js"></script>`
7. Make any further edits you wish to make within the config file.
8. If you want to use your own CSS file for the editor add a new line after the last `theme_advanced_****` item and enter
`content_css : "<?php echo WEBPATH; ?>/themes/yourthemename/content.css",` <- make sure you have the comma at the end.
9. Create your own content.css file in your theme folder or copy one of the tiny_mce theme css files located in
`\zp-core\zp-extensions\tiny_mce\themes\advanced\skins\default` and place that in your theme folder and then edit it to your desired requirements and styles.
10. Upload the new tiny_mce folder (and its contents) in the plugins directory and your new theme content.css file to your zenphoto site.
11. Login to your zenphoto admin and go to Options, Plugins, Tiny_mce and then select from the drop down selects your new tiny_mce config files and apply (save).
Your tiny_mce editor for your articles etc should now be working and using your own config files and content.css file.
For more information of config options for tiny_mce go to http://tinymce.moxiecode.com/ and have a look at some of the examples to see what you can do.
I hope this helps someone
Cheers
GW