I'm still very much a noob and trying my best to understand the ins and out of debranding.
However, I did find a way around the restrictions to use ring tones that doesn't involve debranding. The problem isn't a KB restriction (at least in my case, I have a W760a from ROGERS). All you have to do is to DRM the MP3 tunes and your phone will happily accept them .
You can download the program here
PS here is my noob question. If you debrand a phone, can you restore the original branded firmware?