Got a response back from Telenav Customer Support regarding availability for the Storm 2 (my device is the 9520 so i am unsure how it will work however as both devices have pretty much the same OS 5.0 i wil treat both devices as the same)
In your BB Browser go to www.tnclient.com
and select the following option: -
Select Blackberry9500 - (build 126.96.36.199) option
Once this is done you download the app onto the phone. Once this has been done you run Telenav GPS Navigator and then select the language you want from the options available (If you are presented with APN navigation, you are advised to "press the trackball to proceed" in other words click the screen - i wasn't brought to this screen so this might only be applicable to users running OS 4.7 possibly although i can't confirm this).
At the LOGIN screen, your phone number will already be registered however i had to add my country's area code (i.e. i live in the UK so i had to enter 44 as in +44 so american users will just enter 1 for example - if your number is not already pre-populated just put it in). In the PIN number field, type in a 4 digit pin you will remember and enter it.
This is a free trial link so far so no Activation Code required for those who haven't had an account with Telenav. For those who do have an account with Telenav it might prompt you to enter the 16 digit code of your active account in possibly although i cannot verify or find this in the menu.
The turn by turn voice navigation is excellent - i had my Storm paired up to my car's bluetooth headunit and the A2DP control is superb!! If i'm listening to a track on my BlackBerry, it pauses what's playing, gives me the navigational command/instruction then resumes the song from where it was paused after speaking the direction!
The only downside is that the on screen map is laggy (borderline slow) on updating itself however as i have the voice navigation given to me in real time i don't mind so much. I would probably imagine the laggy performance is down to either the OS/Memory or possibly the GPS chip in the phone...
Overall it's a highly recommended product!