CS6 is the same when it comes to installation of plug ins. Just direct the program into the plug ins folder in CS6 (again being sure to close it first). Make sure that the plug in is in one location to start with. There might be issues if you have it, say, on a flash drive and again in Program Files.
If they are freebies, like "Harry's FIlters", there are always newer versions you can download. Also check to see if they needed a license key to start with. You may be able to contact the site where you got them for a new license key.
If, however, they are "borrowed" plug ins, you might be SOL and will have to find more compatible ones. As Bob mentioned, if we knew what they were, we could be perhaps more precise.