Possible to make `sort-sexps` take a sorting function?

My lisp-fu is not so advanced to do this, but I'd love ot pass something like, `(sort-sexps beg end &optional accessor)` to sort specifically on a certain element of a list (i.e., sort all defines by `cadr`).

Looks like the `collect (cons (buffer-substring...)` code needs to be modified, but I'm not sure how to define a searcher for a certain element of each read list and return its begin and end points in the buffer.