[Logician]

As a matter of fact, your best bet is to change your rules and make it clear that if someone intentionally passes around a censorword, he will get banned. G-force's User Warning hack may help you achieve this goal too. This is because:

1- There is no way to stop a creative user pass a censorword. You can ban word "Microsoft" and a few more similiar versions like "Micro Soft", "Micro$oft", "M.Soft". but there are literally hundreds of ways to mean it like:
"M i c ro s o f t", "MI CRO SOFT", "Miicrosoft", "M-i-c-r-o-s-o-f-t", "Micro+soft". I think you get the idea.

So if a user intents to use the word, this way or that way he will. However according to me, if a user notices that forum administration is banned the word when he first used it in the normal form, then edits his post to make it visible, by all means he deserves a good ban.

2- Filtering is quite server intensive and that is why it is restricted with 250 words and there is no "user specific filters" in vbulletin. Say, I'm using "show 40 post per thread" setting here in vb.org so vbulletin display me 40 posts per thread. Say each post has 150 words in it which makes 6000 words per page. Say admins set 250 filter/replacement words in options and I have my own of 250 which makes 500 words. Can you imagine the server load and slowness of process if vbulletin passes through a 500 words list to match them in 6000 words in every thread I read here. You'll soon get the server on to its knees.

So maybe my message did not help you but it may clear the ground why the help you are asking is not so easy to get in technical aspect.