I have posted the sugestion below in Chess.com Feature Request and Wishlist #6 at post #739 page 36

http://www.chess.com/forum/view/community/chesscom-feature-request-and-wishlist-6?page=37

And would appreciate any suggestions as how to do the queen side castling, 0-0-0, with the black rook in a8 and king in b8. 

So here is the text of my post that you also can access with the link above:

In a chess960 game it is very difficult to figure out how one should proceed to castle, for example if my black rook is on the a8 square and my black king is on the b8 square, how do I do the queen side castle, 0-0-0? what do I move first and second?  

Maybe the board interface should have separate a-side (O-O-O) and h-side (O-O) castling actions, for example: a button or menu item to select for castling.

Ideally, the programmation should also be able to detect a king or rook move that cannot be anything other than a castling move and consider that a castling move when any piece, the rook or the king is put on it's final position for castling.

Alternatively the King only is moved to his final castling position, but in this case if the king has to move only one square it could be considered a king move creating confusion, then a window could open up and ask if this is a castling move or a king move only to avoid confusion.

Whichever way is better to do the castling I will be happy to be able to have the option to use it.

And I would prefer a button to choose castling on either the king side or queen side, seems a good way to do it.

A suggestion for the button location is above the submit move box. And once I select one of the 2 options to castle, king side or queen side, there should be a message asking:"are you sure you want to castle and do specify king or queen side".

Or, you could drag your king onto your rook, whic works all the time

Not clear for me, can you elaborate on how to drag the king onto the rook.

What do you mean by :"onto".

Help me here as you have the solution to my problem.Thank you.

Click the king, then click the rook. If castling is allowed it works every time.

 Are you saying just click on the king first and next click on the rook, by the way right or left click on the mouse? or are you saying click on the king first , right or left click on the mouse and position the king in it's final square position and do the same for the rook or are you sayiing just click first on the king and very next on the rook? and again right or left click button on the mouse as the right click button has a number of options while the left button has none.

And if the right buton then what option do I select.

Thank you. 

Put the king right on top of the rook your castling with,that will work in any legal castling position.

Just left-click the king and rook. Two clicks total. Everything else happens by magic.

Use the analysis board to try it out.

Move the king onto the square that the rook is currently occupying, in the same manner that you normally make moves on the site. It's really pretty simple.

Thanks to all and 2 suggestions work fine to castle in chess 960:

1. Putting the king on top of the rook by clicking the king first with a left button click of the mouse and next clicking the rook with the left buttom of the mouse again, if the move is legal it will be performed.

2. You can drag the king on top of the rook and again the castling will be done.

3. there is another way of doing it and it is the same way that you play a move on online chess.

Again a million thanks.

Thank you for explaining the above and I found it of practical value.  The method I like is to place the king on the rook and I suggest that this method is publicised in the following when it is prepared:

http://www.chess.com/learn-how-to-play-chess.html

http://support.chess.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=721