I created a new theme that only contained SMS modifications and dragged it higher than my main theme in winterboard. If you don't know how to SSH or create themes, there is always help around here, and check out my blog link in my signature, I have some blogs that deal with changing icons, etc with SSH. hackthatphone.com also has excellent SSH tutorials.
But as always, SSH allows access to core files in your phone, so unless you're pretty tech savvy and feel comfortable doing so, I don't recommend it, as deleting certain things can cause you to have to restore, or mess up your phone pretty badly.