Thank you so much for all your responses. :-)
I was just searching for everything starting with 01 01 04 20, because right after that starts a private key in the wallet file. After that i used bitcointools to convert them into WIF-format and imported them with the importwallet command from the debug console. It worked for unencrypted wallets i created for testing purposes so fingers crossed.
Iam gonna try the decrypt.cpp. Thank you for the hint