Plenty of folks with the current style CVO air cleaner covers have used them with the round K&N style filters, even though H-D indicates they won't work. The reason is that the older style covers have a round center section that fits the round end of the filter perfectly, and thus the cover is fully supported. The newer CVO style covers have a rectangular center section that doesn't match up as well with the outer end of the filter, and that can cause issues such as stress cracking of the center nut in the filter from vibration and movement of the cover. Many people on the site have indicated they've had no problem, but to be safe you may want to provide additional support. Place the filter into the cover (off the bike) and line it up with center bolt, and then you will be able to see where additional support is needed. I don't have any photo's or drawings to help explain it any better, you just have to see it for yourself.
Jerry