Install Johnx's a2dp deb (which is a bunch of scripts to save you the hassle of tweaking the config files yourself. Many thanks Johnx, I definitely use them), you will then be able to use a2dp (with the encoding done by the main ARM processor).

If you want the encoding to be done by the DSP rather than the ARM, then (i.e. as well as Johnx's a2dp deb) install my sbcenc "package" (tarball + deb + installation script) and this will install the DSP task, config data and a patched version of bluez-utils which uses the DSP rather than doing the SBC (the codec used for a2dp audio) encoding on the ARM.

Hope that makes sense