Auth with Existing Database

I am converting a ROR website to Cake and the existing database has "password", "email" and "salt" for the User.

How can I modify Cakes Auth to use the salt and the user entered password to authenticate?

 

It's currently using bcrypt hash in conjunction with the saved user salt to authenticate. So I need a way to incorporate this method in Cake.

 

I know / have existing sites using the Blowfish (bcrypt) so that part is fine, I just need to apply the salt with the user entered password in the Auth->login() is where I am at a loss.

 

Any ideas / help would be appreciated.

 

Thanks

Dave