Alter existing vBcode

[Ragnarok]

I'd like to change the [url] code on my site to display the following when a user is not logged in.

-You must be logged in to view links on this website-

How do I alter the pre-existing vBcode to do this for me? The vBcode Manager only allows me to edit my custom vBcodes.

[cheat-master30]

There's already a really simple mod for this here:

https://vborg.vbsupport.ru/showthread.php?t=123415&highlight=hide+links+guests