Photoshop Elements version 11 is available for free trial for 30 days.
But it looks like you can get version 10
free.
Be careful installing (in case of virus), I haven't installed from here myself.
http://downloads.phpnuke.org/en/down...p_Elements.htm
It's only a cut-down version of Photoshop but it has all the tools you need for editing skins.