For all intents and purposes your username is permanent. Previously your account was tied to a unique user ID and your profile was a pop up box with some information. That changed in 2007 when the site was redesigned and each profile was given it's own page and url based on the user name. Your username is part of a permanent page of the site that has a specific URL (username.newgrounds.com)
To change your username, the staff need to change the URL that leads to your user page.
Simply PMing Wade is not going to get you a name change because it is entirely at his discretion to do it or not to do it.
If it's been that long then I would guess he's not going to do it for you.
If you want a desired username you are welcome to make a new account with the name you want. If you want to use the same email you used for your current account, you will need to change the email for your current account so that you can create a new account using it (otherwise you get an error message saying the email is already in use for an account).