MD-81/MD-82 (Nikkei): Where's the Radio Button??

I have the McDonnell Douglas MD-81/MD-82 from Nikkei Business Publications but can't figure out how to get on the radio. It does not appear to have the standard "headset" button next to the other ones. Is the button hidden somewhere or is there another way to come up on the radio?

Also, I like some of the sounds with this model including the "Pull-Up" warnings and the elevation warnings on approach ("400", "300", etc.). Could do without the flaps noise though. Is there a way to include some of these in with the sounds of other aircraft without a wholesale replacement of the sound folder?

Thanks!