Updated ps cs6 camera raw to 8.4 on mac os 10.5.8 now cannot revert to 8.2

You must mean mac os x 10.6.8 snow leopard, not 10.5.8 Leopard

See if this helps:

http://helpx.adobe.com/x-productkb/multi/camera-raw-84-support-policy.html#Revert%20to%208.3%20on%20Mac%20OS

Just curious... did the revert from CR8.4 to Ce8.2 resolve the issue? If so please file a bug @ Adobe - Feature Request/Bug Report Form

It's a bit of a work around, but you can uninstall PS CS6 [and perform a clean install / don't update the software afterwards for camera raw] and manually install the CR 8.2 update:

CS6

http://swupdl.adobe.com/updates/oobe/aam20/mac/PhotoshopCameraRaw7-7.0/8.2.67/setup.dmg

kglad is right the update 8.4 should not result in issues. Please check the Photoshop Family Customer Community for issues.

you can use belarc advisor to recover your installed adobe program serial numbers and that's something you should do now if you have no other way to retrieve them.

and cr 8.4 should do everything cr 8.2 can do (and more).

but if you want to replace, go to C:\Program Files (x86)\Common Files\Adobe\Plug-Ins\CS6\File Formats\ and replace your Camera Raw.8bi file