Yes I certainly could of used a how-to a month or so ago, probably still could. Thanks to a few, particularly Induane and Illori... some ramblings, deductions etc.. Please correct/append as needed. I used Windows & Photoshop for the most part, later I used Gimp for Windows to ensure PNGs were RGB/indexed where neccesary. (What can I say, I'm a web developer, a 0.5MB image file seemed blasphemous)
What I did...
With Winzip installed, browsed to the skins directory, C:\Program Files\PlaneShift Crystal Blue\art\skins\ in my case,
Right clicked one of the bundled themes, on context menu select
Winzip >> Extract to C:\Program Files\PlaneShift Crystal Blue\art\skins\THEME_NAME
rename the directory to what you want to call your theme, you'll be talking & typing it, so shorter is better, mine's called prpl
edit skin.xml put in your <name>, <author> and <description> info
edit/review imagelist.xml take note of the "trans" values for the mouse cursor, typically 255,255,255 aka white
I edited mine to be grey since at one point my mouse pointer had pure white in it
<trans r="99" g="99" b="99" />
whatever value you pick, be consistent and always use that color/pallete entry for transparencies where applicable.
When saving images, ensure your PNGs are in RGB mode, except the mouse cursor, it should be saved in index mode, using the correct transparency/alpha channel value defined in imagelist.xml
after modifying your theme, browse back to your new theme directory , C:\Program Files\PlaneShift Crystal Blue\art\skins\prpl in my case..
Right click, create new winzip file, I of course renamed mine prpl.zip
ALT, E, I to invert the file selection, you should have 5 items selected, 3 folders, 2 xml files
Right drag the 5 items onto your zip file , Winzip should open, the default options are likely fine, but I uncheck everything leaving
action on "Add/Replace" and Compression at Normal Click "Add"
Copy the new/freshened zip file up one directory, to :\Program Files\PlaneShift Crystal Blue\art\skins\
Run Setup and select the new theme if needed and launch psclient
When distributing your theme, take a minute or 2 to ensure you aren't including un-needed development files, like PSDs, that make the download bigger than it needs to be.