This mod is more appropriate to use in Mirrored mode in SDT. You can find this option in the Settings.
Her costume can be found here: Mercy Costume
A combination .swf (which has both the hair and costume in 1 file) can be found here: MEGA
The above Google Drive link is to a .zip file, which contains a folder you can drop into your Mods folder of the Loader and instantly have a call to Mercy at your whim (as long as you add the appropriate line to your CharacterFolders.txt file). The .zip folder also includes standalone versions of the hair and costume. I've elected to host the combination mod off-site as I see no need to post what would basically be the same mod twice (the costume and hair are unique, the combo mod is literally just both together).