How to find out the ECDSA private key perfix version for Altcoins? I want to create a paperwallet for an altcoin (Protoshares).

I know the public key version byte is 0x38 (56) and the addresses start with P...

But how do I find out the ECDSA private key prefix? For bitcoin it's 0x80, for litecoin it's 0xb0.

The Protoshares private keys start with 7... if that helps. Any idea where to look at?
Take the private key. It's probably expressed in base-58 encoding, so you just have to translate the number into base-16. The prefix is there in hexadecimal form.

To convert a base58 number to hex, check etotheipi's code. Based on it:

b58_digits = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'

def base58_to_hex(b58str):
  n = 0
  for s in b58str:
    n *= 58
    digit = b58_digits.index(s)
    n += digit
  return hex(n)