Item description:

Installation
You need to have the latest luma for this to work correctly.

WumiiboHelper
WumiiboHelper is an easy to to use homebrew application. You can automatically download and install wumiibo from wumiibohelper (or you can follow the manual installation steps below).

If you're installing wumiibo for the first time, you can download WumiiboHelper.3dxs.
Run the .3dsx and select Download Wumiibo to download and install wumiibo (once installed use the second option to generate amiibos).
It has an option Generate amiibos for a game that can produce compatible amiibos for a compatible game right from your 3DS.
Note: This app is not well tested. You can generated amiibo manually by using the generator instead if you if you encounter any error.

Installing manually
Put the 0004013000004002 folder in luma/titles/.
Download the amiibo you want to emulate from here. All this website does is produce a bin file with amiiboID in it, so the produced file can be shared freely.
Put the downloaded bins in a folder and put that folder in sd:/wumiibo. You can also place the bins directly inside sd:/wumiibo. You can have upto 49 folders and inside every folder you can have more subfolders. So if you sort your bins correctly, there is no limit on how many amiibos you can have at a time.
Enable Title patching from luma menu (as shown here).
Open your game and reach to the screen where it tells you to place your amiibo.
Press L+Down+Start to bring up Wumiibo Menu and select the amiibo you wish to emulate.
If everything went successfully, your amiibo should be emulated now. If you want to use your real amiibos, you'll need to disable wumiibo by disabling game patching from luma menu.
User guide
Compatibility game list
Some games freeze after closing wumiibo menu, check the compatibility list for these games. The following workaround can be used to emulate amiibos in such games:

After you have opened your game, press home button.
Open wumiibo menu and choose what you want to do.
Open the game again. Do not try to open wumiibo menu in such games.