As Anope is at present you cannot write to the MySQL DB's from an external source as Anope will simply just overwrite your changes. At runtime Anope only reads from MySQL once at present. And thats when it starts up. After that Anope no longer reads from the MySQL DB it only writes to it.
So at present using the MySQL you cannot set up a web registration service.
If by web register you mean to simply read and list without wanting to write then im sure one of the devs can help you with the flags.