The ability to create new commands or functions by 'programming' is not supported. Since less than 20% of CAD users require and use the latter, Claris CAD provides the customization capabilities required by a large majority of the market.
There are third party utiliies, such as QuicKeys, that do allow users to record macros. While they have not been tested and we do not endorse any of them, some users have reported some success using them.