Thanks for the reply, the above information has been very usefull, and has pointed me to the solution. I want to decrpt some RSA keys that have been encrypted with Pythons m2crypto with AES-256.
Actually opening up the encrypted key you see this as the header.
-----BEGIN RSA PRIVATE KEY-----
DEK-Info is the important part. The first argument is the ancryption algorythm used, the second argument is the salt.
The password is then passed with the salt to PBKDF2 (Password-Based Key Derivation Function) which is what makes the actual key used to encrypt the keypair.