AVRCP is a Bluetooth 2.1 profile, so you will need to go through the MFI program - even then, if your are not the manufacturer for the audio unit you will probably not be able to get the solution certified as you won't be able to get the Apple chip added to the device.
To clarify my answer - According to this document iOS has support for AVRCP, in conjunction with A2DP to allow external devices (such as a car stereo) to play/pause/skip tracks being played by the iOS device. Controlling an external device from your iOS device is not available to an app