Well, I don't know how the wiring works in Fils, but first I need to know what exactly you mean by three way... The phrase varies between countries.
Do you mean two switches controlling the same lamp or three switches?
If you just mean two, then you can just put a 2-way dimmer switch at one of the light switches and use a regular 2 way switch at the other end. You can't put two dimmers in usually, though Varilight do make a Master and Slave system where you can, though I think that's only for the UK.