The idea with the resteal is to reraise when the button or cutoff raises against your blind. This can be effective if the player(s) in question are raising fairly automatically. If, every time you are in the BB, you are facing a raise from the button, you are in the sort of situation where you probably should reraise.
The reraise accomplishes two things: One, it shows the button that you are not going to be pushed around. Two, it makes a statement to the other players that you are not playing scared. However, it is best to do this with a playable hand...
How much depends on a lot of factors -- the usual. Relative stack sizes, the size of the original raise, the probable range of hands from the raiser, your hand, your table image. If you are perceived as a LAG, your reraise will not be feared as much as if your image is TAG. If the raiser has put in a standard raise (3-4xBB), it is sometimes enough to double that to win the pot outright, if your stack can afford the raise if you lose it.
I don't advocate the shove in this position without a premium hand. Actually, I don't advocate a shove at all -- why risk your tourney life when reraising to double the raise can do the trick? It will usually slow down or stop the raiser who has nothing but position, and will reveal the raiser who actually has a hand.