Load ATITC textures during runtime

I have a custom tool that generates and encrypts textures depending on the hardware/platform for Windows, Linux and Android and creates a texture dictionary.

Currently I am able to load PNG, ETC1, DXT and PVRTC textures from my raw texture dictionaries but I am unable to load ATITC textures for Adreno GPUs.

To create ETC, DXT and PVRTC textures I am using the PVRTextToolCLI (the command line version).
To create ATITC I am using the “The Compressonator”.

The code I am using to load PVRTC is:

var data = File.ReadAllBytes ("/sdcard/xxx/texture.pvr");
bgTexturePVr = new Texture2D (this.GraphicsDevice, 1024, 1024, false, SurfaceFormat.RgbPvrtc4Bpp);
bgTexturePVr.SetData (data, 67, data.Length - 67);

To load other formats I just change the surface format and change the header length. But I can’t find any format that is suitable for ATC textures…

Which SurfaceFormat should I use to load ATC ARGB textures?
Or which method should I use to load the raw data from an ATITC texture?

Thanks in advance