Block 'new registration' updates in activity stream (BP 1.7)

How do I stop new user registrations appearing in the activity stream in BP 1.7?

I have tried this plugin: http://etivite.com/wordpress-plugins/buddypress-block-activity-stream-types/

and this hack:
http://blog.etiviti.com/2010/02/buddypress-hack-remove-new-member-registration-from-activity-stream/

and neither seem to do the trick. I'm guessing it's because they're only designed for versions up to 1.5.1

I can't seem to find anywhere else that does this.

Any ideas how to go about doing this?

Thanks!

D