* Highlight all matches in the =*Locate*= buffer like in the =*Occur*= buffer:

#+begin_src emacs-lisp
(add-hook 'locate-post-command-hook
          (lambda ()
            (save-excursion
              (goto-char (point-min))
              (when (or (re-search-forward "Matches for .* using filter \\(.*\\):" nil t)
                        (re-search-forward "Matches for \\(.*\\):" nil t))
                (highlight-regexp
                 (match-string-no-properties 1)
                 'match)))))
#+end_src

* Ignore case in locate command

#+begin_src emacs-lisp
(with-eval-after-load 'locate
  ;; Redefine ‘locate-default-make-command-line’.
  (defun locate-make-command-line-ignore-case (search-string)
    (list locate-command "-i" search-string))
  (setq locate-make-command-line 'locate-make-command-line-ignore-case))
#+end_src