Unfortunately I would have to recommend against it. I went way down this path, tried multiple spacers, and ran them for a bit, but it cause issues. I've run spacers on my Audi's with no problem, much easier and safer when they user lug bolts, instead of lug nuts. The trouble with the X is that because it uses studs in the wheel, you can't replace them with longer ones, and have to use a spacer with it's own set of studs and this is difficult to make fit safely. You have to use low profile nuts to attach the spacer and I had issues with the main studs and/or the bolts not clearing the wheel, especially on the front. I talked to all kinds of professionals, and they strongly recommended against it. It can cause damage to the bearings and puts extra stress on the vehicle that could put your warranty in jeopardy.
If you really want the flush look, which I love, just bite the bullet and buy custom rims with the offset you want.