The intrinsic point of steampunk is thinking about your character, then thinking about how to alter them so their powers/armor etc would work off of steam while bending towards schools of victorian fashion.
Since SailorMoon doesnt particularly have a lot of moving parts, your accessories will be the biggest parts of the "steam punk" genre.
for example - check out this "sailormoon steampunk locket" http://siplbunny.deviantart.com/art/...et-7-190585584
some concept for a steampunk SM: http://24.media.tumblr.com/tumblr_lz...2fnuo1_500.jpg
Hope that is helpful! I look forward to seeing your project!