Lots of people have asked how this is done; understand that the big issue here is that your TBB PIN code is not the same as your TBB SIP password. What happens when you fire up your TBB software is that it hits a website (counterpath-act.primus.ca) with your PIN, and that website returns all the settings (SIP gateway, password etc).
To get your real sip password, copy and paste this bit of HTML onto your desktop, and click it in your browser
fill in your phone number/pin (the IP can be anything really)
Then use the info that comes out of this form to get your settings like:
plug those settings into your VOIP software, and voila you're in business