There are two versions of the Lighter. The Normal Version and the HueShift version. Both use the same Prefab with the only difference being the Menu and Parameters.
Find the Prefab in the ‘RuneFox/Lighter/_Prefabs’ folder and drag it onto your avatar so that it becomes a child object of your avatar.
If you need to scale the prefab only scale the Parent Gameobject. Try not to scale any of the gameobjects inside the prefab as that may result in undefined behavior.
Right Click on the Prefab and select Prefab→Unpack. We need to do this in order to drag the objects out of the prefab onto the avatar’s armature later.

Expand your avatar’s armature and navigate to the Left and Right Hand bones. These are sometimes labeled as wrist bones instead of hand bones.
Drag the left and right hand targets so that they’re children of the hand bones.

Move the hand target objects in the scene to reposition the placeholder lighter meshes so that they’re in the palm of your avatar’s hand.

For the Holster, drag it into the armature where you want the holster parented, in my case I chose the spine as I’m attaching it near there.
Move the Holster object to move the lighter around until it is in the place you want it. Make sure that it is in an area that is easily accessible as you need to put your hands in contacts on the holster to equip/unequip the lighter.

Here we’re merging the FX Animator and Parameters of the Lighter onto your Avatar using Avatars Manager 3.0. If you’ve manually added other complex assets to avatars before this part will be familiar to you.
Open up the VRLabs Avatars 3.0 Manager window by selecting it from the VRLabs dropdown.
Drag your avatar into the Avatar field on the manager window or select it from the popup by clicking on the little target on the right side of the field.