Timer in AudioPlaybackAgent

I have an Internet radio app that uses BackgroundAudioPlayer.

I need a timer in the Audio Playback Agent that will update the track title of the currently playing track of the BAP that is pulled from the Internet radio station's API.

Adding a DispatcherTimer into the Audio Playback Agent gives me a cross-thread exception, and using:

Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                // Code
            });

Didn't work.

I need the code in here because if I put the update code in the app itself, when the user navigates away from the app the updates stop (much unlike Windows 8's behavior).

I can't use Scheduled Agents since they only run once every 30 minutes (IIRC).

Is this possible or can this not be done on Windows Phone?