I can't remember exactly, but there's a registry and icon tweak that you have to do for it to work for any other GPS program, but it wont work the same way as when you click on Address or Home and have TomTom installed. Usually, since it comes with either CoPilot or TeleNav it is coded so it performs that action when you click it on Navipanel (Example: Click Home on Navipanel and it'll open CoPilot and automatically enter your Home address and all you have to do is press "Go"). The registry and cfg file hacks can help, but you're gonna have to search for those because I can't recall from memory.
As for the "free" Telenav, it's only a trial period. Meaning after 30 days it's gone. Unless you hard reset and enter new username or whatever information it asks for you won't be able to continue using it free. No such thing as "free" with Telenav since you have to connect to their servers to use their program (which is complete bull**** in my opinion).