Well, the computer that I had Sins on with the mod has encountered a strange error and bluescreens on anything other than safe mode. I can still grab the files I was working on and still have the 'extracted' images, but I can't work on anything for now. I intended to get some screencaps of my progress so far but it looks like it won't happen now...
I managed to replace the icons for the TIE fighters, assault gunboat, both Star Destroyers, the Interdictor cruiser, the Modified and Regular Nebulon-B frigates, the Modified Corellian Corvette, the Corellian gunship (with a slight modification to the Corellian corvette icon), the Rebel fighters, the Dreadnought, and I replaced the hangar defense with a platform icon. The Strike cruiser icon was replaced on the left menu but not ingame.
Also, the OP is wrong: B-wings are being displayed as Y-wings, not the other way around (incase nobody pointed this out already...).
I do have icons for mines, and I thought about trying to replace them, but for the ships already existing in SINS I wouldn't know how to begin modifying them. Before my computer borked I did look at the text file Evaders mentioned but couldn't make any sense out of it.
At the moment the only thing I can do in terms of icons is make up new ones, but I won't be able to test them. I could post them here and maybe Eville or someone can introduce them. Then again, Eville hasn't commented at all on my efforts, so I may or may not have any 'official' support for his mod.