Well if Photoshop will allow the slicing and saving in Targa 32 bit format with the alpha channel retained you should then be able to run the slices through my ConvImX batch convertor program (on the beta page) to convert to DXT3 or Bmp32.

No Sir. Photoshop allow to save slices only in the webdesign related formats GIF, PNG-8, PNG-24, JPG and WBMP. So all without alpha. :(