Custom Firmware for iPhone 4?

[huckstah]

iPhone 4
Firmware: Unknown (passcode locked!)

Trying to get past a pass code lock from a phone sold to me on craigslist. Restored the iPhone but I get error (1016, i think?) and it will not let me restore. I had a similar problem with restoring a 3GS to 4.2.1 but I was able to get past it by redsn0wing it to pwned dfu mode and then restoring it through itunes with a custom firmware. Do I simply need a custom firmware for the iphone 4 version of 4.2.1? And if so, where do I get it?

[iPittsburgh]

Ive heard of someone putting the phone into recovery mode and then restoring to current fw to get past the passcode lock.