Try evaluating the following elisp in a graphical session:

(defface special-char
  '((t :box t))
  "Face for special chars")

(defconst RLO #("\u200bRLO\u200b" 1 4 (face special-char)))

(defun set-disp-entry (table idx str)
  (let* ((len (length str))
         (result (make-vector len nil)))
    (dotimes (c len)
      (let ((face (get-text-property c 'face str))
            (char (aref str c)))
        (aset result c (make-glyph-code char face))))
    (set-char-table-range table idx result)))

(set-disp-entry standard-display-table #x202e RLO)

(ucs-insert #x202e)

Afterward, I get a character that looks like a double-boxed RLO.  Image
included: