are you guys sure this is possible? i know for a fact that the OEM e36 plastic headlight covers can NOT come off unless you bake them and mess up all the seals.
To be honest with you chris, go with the new projectors. just with projectors alone your increased light will be incredible! And since it is a glass headlights cover it won't wear and look as shitty as easily, plus if it break you can easily replace just the cover.
another possibility is that your stock xenon can transfer over to your new projectors. i would take a lot of time to research this, im sure someone has tried, but it seems silly to buy new xenon for your new lights when you already had it.
hope this helped.
PS: adding DDE to headlights when its not already installed for you is tough i hear. the rings are VERY fragile.