You know i did try this earlier and im sure i did it right but to no avail however i've just done so again and it's working :)

I'll go hide in the corner :)

Just so you know the user would *never* type the regex out as such. they'll ultimatley be entering it via a gui interface and sending it off to a server to store in a config file, the regex is used in a print system i've been developing to re-format the usernames into more readable forms and it's used by the input filter :)