This is fairly easy to do

1 - Add the Slope indicator to your chart.

2 - Goto View .... Navigator.

3 - In the indicators section highlight moving average

4 - Hold down the Ctrl key and drag the moving average to your chart.

5 - Set the period and type of ma you want.

6 - In the Apply to drop down box choose Previous indicators data

The ma will then refer to your slope indicator.

You can do this with any indicator on the chart or even on a seperate window.