Well, here's one way to get those page references, using filters:

(defun my-odt-filter-pagerefs (text backend info)
       "Make page references, not textual references in ODT export."
       (when (org-export-derived-backend-p backend 'odt)
             (replace-regexp-in-string "text:reference-format=\"text\"" "text:reference-format=\"page\"" text)))

(add-to-list 'org-export-filter-link-functions
                  'my-odt-filter-pagerefs)

(Whee! I just wrote my first export filter.)