I'm using the following function, adapted from a ru_emacs posting:
(defun reverse-input-method (input-method)
"Build the reverse mapping of single letters from INPUT-METHOD."
(list (read-input-method-name "Use input method (default current): ")))
(if (and input-method (symbolp input-method))
(setq input-method (symbol-name input-method)))
(let ((current current-input-method)
(modifiers '(nil (control) (meta) (control meta))))
(when (and current-input-method quail-keyboard-layout)
(setq normal-local-function-key-map (copy-keymap local-function-key-map))
(dolist (map (cdr (quail-map)))
(let* ((to (car map))
(cadr map) (char-to-string to) 1)))
(when (and (characterp from) (characterp to))
(dolist (mod modifiers)
(vector (append mod (list from)))
(vector (append mod (list to)))))))))
(defadvice* ignore-reverse-input-method around (read-passwd quoted-insert)
(let ((local-function-key-map normal-local-function-key-map))
Caveat: some previously unbound combinations in the English layout will also be remapped this way, e.g.
M-@. As it does not extend to any already bound combinations, not much of a problem IMO.