I bought some adapters off of eBay for my 95 Civic. Unfortunately I can't find any adapters for your vehicle year.
If you can find some, these worked great for me:


I was too lazy to make some adapters out of MDF, but I've done it before.

MDF adapters would be the best way to go. Just REMOVE (don't cut - unnecessary permanent damage) the plastic housing brackets. Get some 3/4" MDF and a jigsaw. Whatever you do, don't use plywood or anything other than MDF for that matter. It will not sound good, and it will probably vibrate, resonate, or rattle.