Actually, I was able to do this.
Here is what I do. I added a field called AccountEnabled and it's a boolean. When the user first registers I add them to a group and do not set the AccountEnabled. So they are disabled (0) until someone approves them (or enables the account)
If they try to register again, I check to see if the email is in the db and what the AccountEnabled field is set to. If disabled, I tell them that their account is still being reviewed.
If it is enabled then I send them an email with their login information.
If they try to login, I check to see if the account is enabled or disabled. If it is disabled, I don't let them login.
I hope this helps.