Converting from Cubecart - password conversion?

Hi all, I've been reading about the MD5 + salt hashes used in Zen cart, but cubecart uses a straight MD5 hash, and I want to convert all my customer's passwords to this new type. Is this even possible? I've been playing around with a test php file to see if I can reverse engineer the password out of the salt, but it doesn't appear that I can.
I'm hoping not to lose the passwords.

bump this thread.

No, you can't reverse the encryption on the passwords. That's why they're encrypted.

You might be able to get a script to work by doing something like this:
a) retrieve the md5-only password
b) run zen_encrypt_password() on it to get a salted password back
c) store that salted password in place of the md5-only pwd
And of course test that it's usable afterward, before running it on your whole list of customers.

Note: When bumping threads it's customary to add more information about what you've tried, what's worked, what's not worked, etc. Explain more about the bigger picture in case people aren't understanding what you're asking. There's often a reason why a post goes unanswered. Try to resolve that by posting more helpful info.