There is a free program I use called irfanview it can reverse the pallet of the skin with the click of a button [ Image > Swap colors > RGB= BGR and vs versa ] comes in real handy it can't save as .dds but you could use it to prepare the skin before and after editing before saving as .dds out of photoshop. If the color mixer isn't your thing then this will help, or if you just want something simple in modding for once
just save out as a .TGA or .bmp then finish the job in Photoshop can also be used as a screen cap util
get it here : http://www.irfanview.com/
I also use xnview also free and powerful it can save out as .dds but appears to corrupt the .dds images unfortunitly.
However It Also has the same colour swap function as irfanview [ Image > Swap > RGB= BGR and vs versa ]and can read / write many, many image formats as well as play video files. It's great to use to open even multi layer .psd's without the ram overhead of photoshop if your just browsing, it has decent image editing tools too, batch conversions, slide show ect.. not bad for free
Photoshop is still the real powerhouse for image editing though.
get it here : http://www.xnview.com/
I hope these apps help I'm a digital artist and Photoshop is my baby, but setting either of these to be your windows default image viewer can really help on a daily basis, when opening / browsing .dds' or .tga's even .Max files that windows fax viewer can't. It also functions as windows explorer with thumbnail view. I don't leave home without them