you also need to get over the fact that this doesn't work while disabling javascript, while built in xslt doesn't need javascript. on the other hand though it's not a big loss given that xslt isn't any safer. anyone who turns off javascript probably ought to have turned of xslt as well.
but that just aside. the last time this was discussed a year ago i actually tried to find a working solution to load xslt through javascript and could not find any.
i only got as far as verifying that js can be loaded from an xml mimetype. xslt implementations in js also exist. what's missing is the wrapper code to load the xslt library and run it over the xml and xslt files.
perhaps now with this seriously being needed by a few sites someone will have the time to get this working.