I am trying to do the same thing but not really getting anywhere as yet.
I use a wordpress theme called Premiumpress which has its own built in registration. When BP is active it bypasses the premiumpress registration and sits at http://www.mysite.com/register (this is a blank page)
I need it to direct to wp-login.php?action=register
Would this command in the post above disable the BP direction and revert to this?
I would be eternally grateful if anyone has any suggestion how I can keep BP enabled yet bypass the registration.