How to change email text for new users (Multisite)

Hi,

on multisite blogs when adding a new user from the admin panel the new user gets an email with his login, password and the link the the dashboard login.

Problem is: even if he’s eligable to create a new blog there’s no link to this form – not in the email and not from the dashboard.

What is the easiest way to add him this possibility? Is there any nice way to add such a link to the dashboard? Or probably change the email content?

Thanks,
Frank