I wish i could offer more specific help, but it may be more helpful to see if any other generations or levels of shimano hubs have dust covers that're compatible. I rebuilt an LX hub with a leter-gen deore hubs guts, once. All the parts fit and worked, although i've been told that the plain deore has "worse" bearings. Either way, they've lasted a good long time.
I know that xtr has some proprietary, exclusive features. Of course, many of these features trickle down to other groups. I wish that shimano would be more transparent with cross-compatibility info, but i reckon they'd rather sell more hubs than dust covers?