So I've been playing on a ROM of White 2 ( so awesome )... and I really want Flareon.
The most info I was able to get was that I needed to down in the desert ._.
In Desert Resort, it's:
>South of Backpacker Haruko (hidden) -Bulbepedia
So just use the Dowsing Machine until you find it.
In Yamaji Town, it's:
>On the hill north of the Pokémon Center -Bulbepedia
Well. this one is easy enough to find.
Hope This Helped :D
Places to find in B/W 2:
Source: Bulbapedia/Fire Stones
Hope I Helped Ya!