Just wanted to say that I tried to do this a couple weeks ago when I found that fix, but it didn't work at the time. I guess they did an update to the wireless tether app, and that, along with the firmware fix, got wireless tethering working on my rooted Aria.
It's somewhat slower than I was hoping for, but it works.
-edited to add-
I enabled WEP encryption, changed the key, and it still works just fine, not that WEP really provides any sort of protection, but at least it works.