Custom migration to ~/.xemacs/options.el

So, customize puts its variables into ~/.emacs according to a heuristic I haven't groked yet fully. (Needless to say, this was a bad idea ...) What's a politically correct (and preferably simple) to determine the set/region of forms in ~/.emacs under the control of customize? Can I search for (custom-load-themes ...) or (custom-set-variables ...) and take the region from there to the end of the file? Or can I take all forms starting with (custom-... ...). Or what? -- Cheers =8-} Mike Friede, Völkerverständigung und überhaupt blabla