Got Kagu and A2DP working, which also means mplayer. mplayer gui doesn't work, but all you need is mplayer itself working for A2DP. The problem getting bluez and mplayer installed was the new version of dbus. It's changed from /usr/lib/libdbus-1.so.2 to /usr/lib/libdbus-1.so.3. All I did was symlink .3 to .2 and a forced install of the two packages. Then I edited the install.sh script milhouse did to skip installation of those packages. Works like a charm.

Quick and dirty instructions:
Install Kagu through normal means. I just installed it by the .deb directly. It complained about something(I think dbus not being configured properly), but still showed up on my menu.
Follow the instructions the here. gainroot is already installed, it looks like. Go until you're supposed to becomeroot and do ./install.sh again. It won't work. You'll need to do the following:
Then you'll need to change install.sh and just delete a pile of lines. Basically from line 12 to 21, delete or comment out. Run it like that as root, and it'll do its last configuration and tell you to reboot. After that, Kagu works with A2DP again.