May 19th, 2013, 06:53
You are almost there. Choose file save as/ extended bitmap. When you get to the save pop up, you can select which type of extended btmap you'd like to choose (see pics)
To make using dxtbmp easy (I also work in PSP) I save a copy of my PSP file as "filename_base.bmp" format, which is the PSP file without alphas. Using PSP I put a white layer underneath my transparency work (as background), & save a copy of transparencies over white as my "filename_trans.bmp".
Using DXTbmp I open my "filename_base.bmp", & import my "filename_trans.bmp" as alpha (top right hand corner of the dxtbmp window). You can preview how it will look by choosing preview/transparency, just to check before you save as an extended bitmap. Use different folders to keep everything from overwriting stuff you may want to change, & you can experiment until you get the look you are happy with.