[BD]

I'm not really good at that, but I open the map pk3 files with Winzip and extract the contents of every map to another folder. Then, select all of the extracted files, right click, highlight Winzip, click Add To Zip, click the New button, find the mohaa/main directory, type a filename (such as "user-maps"), click OK, and change the end of the filename to *.pk3 instead of *zip.

In my experience this doesn't work with players skins, weapon skins, or pretty much anything else. The only things I've had luck with are maps and things like crosshairs, scopes, avatars and the like.

Hopefully someone else can clarify, since I know next to nothing about this.