It looks like the javaCV wrappers indeed only embed ARM libraries. I've recompiled the javaCV packages for android x86, you can get these from here:
Please let me know if they are working.
You can mix them with the ARM ones easily, you only need to put the x86 .so files (from inside the x86 jars) inside libs/x86/.
edit: I've written an article to explain the process more in-depth and provide the latest version (0.7): http://ph0b.com/getting-an-x86-version-of-javacv-for-android/