I have noticed in Chess960 games as a whole (individual as well as vote chess games) that the symbols "O-O" and "O-O-O" are inexistent as options.That would mean that castles in Chess960 games are not legal, but they are legal moves in fact.

I play at the Lechenicher SchachServer (http://lss.chess-server.net/) and their server offers those moves in Chess960 games. Same thing at http://www.SchemingMind.com/ 

You can castle in Chess960/Fischer Random games here. Move the king onto the rook you want to castle with, or two squares in the direction you want to castle.

Castles are legal, and many have problem in castling in 960 games.

Best way to castle, is to take your king, and place it over rook on the side you want to castle. Rules are the same, King can not be under + or the squares where King is passing must not be under attack of opponents pieces, and King can not move and castle after that.

In every setup of 960 chess king MUST be placed between 2 rooks, so castle is posible in every 960 game. After castle, King, and rook on side where you are castling take positions same as they would in normal game of chess. That is, for white, 0-0 King will be on f1 and rook on e1 no mater where they used to be before castling.

"0-0" and "0-0-0" why not try this symbols instead of this "o-o" and "o-o-o" i'm not quite sure about this,i just happen to stumble in some forum topic in which i did not pay much attention in it. just wish that this will be of help .