Since Citra has just officially released on Play Store and the author has not yet giving an instruction to install the hacks on Android so I thought I would give a little explanation on how to install assuming that you don't have a pc (You still need a clean copy of Pokemon X and/or Y):
1. Open the app at least one and accept any permissions required
2. There should be a folder named "citra-emu" on your internal storage
3. Inside the folder above, create a folder named "load"; then inside the "load" folder, create a folder named "mods"
4. Download the hack at the first post (EX or WY), and extract it somewhere
5. Inside extracted folder, open Game Files/[Your desired version of the hack]/luma/titles, copy the folder inside it to the mods folder in step 3
6. Final result should be:
Internal storage/citra-emu/load/mods/0004000000055E00/... (if Wilting Y)
Internal storage/citra-emu/load/mods/0004000000055D00/... (if Eternal X)
7. Open the clean rom you downloaded, choose English and check if the title screen show the right name of the hacks
To install optional Viola Nerf, simply copy the "a" folder from "Viola Nerf" to "romfs" folder inside the folder at step 6 (replace if prompt)