I am not sure why you refer to 'fast castling'. Is that the type of castling proposed by Kevin Pacey in his wide-board variants? Neither the Diagram nor the GAME-code produced by it do support such castling.
The Cannon would have to be in the partners set to allow castling with it. How far the King moves on castling is defined in the moves of the King; castlings are defined in the legdefs table as two-leg moves, the first leg being the slide that has to be used to find the partner, and the second leg (only attempted when a partner could be reached) indicates the leap the King should make. Your presets appear to define both 2-step and 3-step castlings for the King.
A problem is that the castling moves you define on the King are not critical w.r.t. the partner they use; any piece in the partner set would do. So it would not be possibe to only allow 2-step castling with a Rook, but not with a Cannon.
I am not sure why you refer to 'fast castling'. Is that the type of castling proposed by Kevin Pacey in his wide-board variants? Neither the Diagram nor the GAME-code produced by it do support such castling.
The Cannon would have to be in the partners set to allow castling with it. How far the King moves on castling is defined in the moves of the King; castlings are defined in the legdefs table as two-leg moves, the first leg being the slide that has to be used to find the partner, and the second leg (only attempted when a partner could be reached) indicates the leap the King should make. Your presets appear to define both 2-step and 3-step castlings for the King.
A problem is that the castling moves you define on the King are not critical w.r.t. the partner they use; any piece in the partner set would do. So it would not be possibe to only allow 2-step castling with a Rook, but not with a Cannon.