And what are you trying to encrypt? You're talking OS changes so teh ones to talk to are the developers at RIM. Shell out the $$ and I am sure they will devote a team to crating a custom OS for you.
But the BB is already encrypted, so really there's no point.
You really need to understand what you're talking about here. Everything IS already encrypted. GPS doesn't even enter into the equation, how do you encrypt GPS? It's a signal translated into coordinates by software.
And if you mean encrypting the actual voice signal then forget it, the receiver would need to accept that kind of thing so you wouldn't ever be calling many people after you implement it. In fact, probably none.