Changing default text on registration page

I have a site in development using wordpress and buddypress I would like to preview some pages to get some interest and feedback from it.

I have disabled user registration but would like to change the text on the registration page from the default “user registration is currently not allowed” to something else a bit more friendly with some information and to include an email address.

Can you let me know if this is possible and how I can do it.

Thank you very much.

Allan