You can castle in 960 and the rules are similar to regular chess and I believe you can castle from any of the starting positions; though there may be cases where only one of the pieces moves.
The same rules apply; can't castle through, into or out of check. King and rook you are castling with can't have moved previously. Neither king or rook can move through occupied squares.
On an a-side castle (queen-side) you place the king where it would go in a normal game of chess and place the a-side rook to the right of the king. Pretty much the same for the h-side (king-side) castle but with that rook instead.
https://en.wikipedia.org/wiki/Chess960#Castling_rules
Can one castle in Chess960 if any 2 pieces are in their normal position (King and Rook)?