To my knowledge he never did. I believe Bartolini makes or at least used to make direct replacement pickups for them, and they get fairly close to the Phil tone if you use flatwound strings. www.talkbass.com is also a good forum for this question.
Alembic also makes an Activator setup for Rick basses with filters. There's a thread with pictures at the Alembic site somewhere about exactly this. That would probably a really cool sound!