I found out recently that altough 2.004.x skins won't work directly with the newest firmware version (2.004.5), but it's easy to convert them, because image numbering is the same.
Here are the steps:
- just download the Resource Editor 1.22
- open the 2.004.x resource.bin file
- click Edit > Export All Pictures and save the pictures to a folder
- open the 2.004.5 resource file
- click Edit > Import All Pictures (point to the directory where you saved the images previously)
- click File > Save as
- upload the resource to your player, and enjoy the skin
That's it, really easy!