what I am going to say is purely theoretical, as I have never tried to brute force private keys.
I don´t think you will have any success doing this.
I think you misunderstand what it is that the OP is attempting to achieve...
What i think you could do is to find a collision. If someone made an insecure private key, by just hashing some passphrase... maybe you could have some luck.
That is exactly what the OP is trying to achieve:
The Bitcoin puzzle transactions were setup as an exercise to see how tough it is bruteforce BTC... and is essentially what the LBC is attempting to cash in on (aside from other "collateral damage" of people with weak keys).
What is interesting is that the addresses in the middle range of amounts (0.056 to 0.16 BTC), which were theoretically "easier" than the addresses with the larger amounts, have not yet been "cracked"??!?