first: if noone answeres, just wait.
second: skin/logo mods are easy. just go to your cs2d/gfx folder, open the file you want to edit with a programm like paint, edit it and save it. the same for /sfx , in which the sounds are.
real MODS where gameplay is different cant be made with the new cs2d
not the team fortress code...
the cs2d source code (the old one, before cs2d max!)
But, if you realy want to do that, you should can BlitzBasic and you have to find the right things in the source code, what could be very hard