Lunacell, BTW, has a demo- and it seems to work in the free GIMP image editor.
You'll need the pspi plugin, though.
http://www.gimp.org/~tml/gimp/win32/downloads.html
get that, extract it to your GIMP directory, then go to Xtrn->Photoshop Plug In settings and point it at the directory where you extracted the Lunacell demo.
Don't open the directory- just click on it once.
EDIT: though it appears you can't set the colors. Bit of a bug with GIMP I suppose.
EDIT 2: yep, gimp bug; the demo of Photoshop elements works.