You can try a hijack mapping for mute/unmute. I'm pretty sure it's in the hijack faq, which you should be pretty familiar with. However, if you're not getting any changes with the stock functions, you've probably got something hooked up wrong. I'll try and check if the mute/unmute shows up on the button codes display when I drive home.

With my parrot, the phone mute had a cool little thing where you picked which port of the ISO harness you wanted the mute wire to go in.

I'm also looking forward to a full review once you get it worked out.

Matthew