Yes.
In the Finder, select any .torrent file, and Get Info (command-i)
In the Open With part of the info window, select Azureus instead of LimeWire
Then use the "Change All" button.
All your .torrent files will then open with AZ.

Hey. Where are .torrent files on mac OS X's?
Tell me the short cut or w.e to find one in finder please~