if i remember right (been a while) you need to download to your directory ex:
C:\Program Files\RedlightCenter\RedLightCenter\resources\male in the textures or attachments whichever it is. then you copy the name ex:
HMAH001_11_Ruby.png. then you open C:\Program Files\RedlightCenter\RedLightCenter and open your myinfo file, place the article you want to wear in the correcet spot, close the myinfo file and save.
go to customize and hit don't change, then hit show changes. If remember right it should show up.
Good luck