I went through all this last night with my N3DSXL had to research for hours even made a post with no answers and I managed to answere it myself by researching a little more on dfferent forums.
1.)Download the Decrypt9.3dsx file ( the one compiled for N3dsxl 9.x named boot.3dsx ) its on gbatemp.
2.)obtain your slotkeybin ( cant link copy right )
3.)download decrypt9-master ( also on gbatemp) you should see ncchinfo_gen.py
4.)click and drag your dumped game over the ncchinfo_gen.py and it should create another file.
5.) copy the created file along with keybin and boot.3dsx to a folder named 3ds ( structure shown below)
make a file structure with the names like this: your 3 files go in the folder decrypt9
3ds/decrypt9/boot.3dsx,slotkey.bin,ncchinfo (of the game dump)
copy that 3ds file containing the files above in the root of your sd card.
run ninjhax to get to homebrew launcher you should see decrypt9 by unknown author run it. if it errors and takes you to the home screen just try again. no need to recopy files just keep re-running decrypt9 through HBL till it runs.