I'm almost certain that you can simply pull the EWSII chip from the DME. What it looks like, I have no idea. From what Mark D'Sylva (who makes EAT performance chips) tells me, the earlier DME is the same as the later (EWSII) DME, except that EWSII chip isn't there. Don't recall the DME code numbers, but it makes complete sense.
Or you could likely just use a pre-'95 (non EWSII) DME. Easy to try if you can get a spare.