Fuels

VirtualFurnaces have their own fuel setup separate from vanilla Minecraft. You can register your own fuels or you can even just register fuels which mimic vanilla MC's fuels.

Registering a fuel

Registering a fuel is simple.
Syntax:

register furnace fuel %itemtype% with burn time %timespan%

ItemType = the item you want to use as a fuel (note: this will only support items which MC currently allows as fuels, this is due to a limitation of MC only allowing certain items to enter the fuel slot)
TimeSpan = the time this fuel will burn for.
Example:

on load:
    register furnace fuel coal with burn time 10 minutes

Registering vanilla-like fuels

Instead of registering your fuels individually, if you choose you can just register all the vanilla fuels as virtual furnace fuels.
Usage:

register all vanilla furnace fuels

This will essentially copy all of Minecraft's fuels as virtual furnace fuels.