Open it in Logic as a native instrument, you should have the option to? My plugins are always searched when opening the program, it then verifys they're legal, sets it up etc etc. Has it not searched for it? If not, you need to put it in the VST folder.. If in doubt, if it works in Cubase - program it on the matrix on there, then export it as an audio file and stick it into Logic. Make sure everything's quantiezed though!