Ok here goes.
I've been mapping for a while, but finally got talked into trying to make some custom skins for some clan friends.

I took a skin that I had downloaded at some point that I hate.
I moved the PK3 to a different folder, Renamed it to a ZIP, and extracted all: Keeping folders intact.
Then I edited all the JPEG's, and saved them back in the exact same place, under the exact same name, using no compression.
I figured if I could get the skin to work, then I would go through Fraggers tutorial again step by step and rename everything with my own names.
Next step. I zipped the folder back up, keeping folders intact, and renamed it PK3.
Heres the rub, when I put the PK3 back into my base/mp folder and start a multiplayer game, the skin is gone. IT doesnt show up as an option to use.
If i take the edited pk3 out and replace it with the original that I hate, and start the game then the skin is available again.
Now I didnt edit the G2skin file or the NPC file, or the shader file, so everything should be pointing to the correct jpegs, just new edited ones.

Is it not possible to skin this way,?
Or do I need to do things the long hard way and start from scratch.
Has anyone else tried skinning this way?

Ok make sure that the files in the pk3 have the right paths.. If u can't select your skin then u probably have a problem with the npc file... SoF2 can be very weird sometimes with the npc files. If u have one extra space or whatever it could stop working. So make sure that the npc file is correct and that u have the right filenames in the g2skin file.

Ok thank everyone for their answers.
Must have been something to do with the way XP zips things.
I found that if I just rename the pk3 to a zip and don't extract. Then i can browse the zip folder, open the jpegs. edit them resave them, then drag them back into the zip folder to replace the originals.
Everything works, and no need to make a new player icon.
The game automatically updates the icon to match the new jpegs.