If you have a repack of the game, check if it comes with the BepInEx directory, in which case you can most likely just drop the DLLs into BepInEx\monomod. Otherwise, follow one of the methods below.
The simple method
To make things simple, Inohara comes with BepInEx and BepInEx.MonoMod.Loader. Install Inohara and then drop the DLLs from releases into BepInEx\monomod.