Yes, that can be done!
The color of the map texture defines how the underlying pixels are modified. If you have a perfectly gray (r=g=b=127) texture, nothing will happen.
So, start with a Gray RenderTexture that has the size of the area you want to distort. Use that texture as the "mapTexture" of the displacement map filter.
Now, when somebody clicks on an area on the screen, draw something in the render texture at that position (whatever RGB values you need for your distortion). Then this part will be distorted.
To understand how exactly the DisplacementMapFilter works, I recommend you look online for examples in Flash/AS3. The class is modeled after the AS3 version. Also, have a look at the sample I show here.
And let me know if you need any more help.