setting encrypted password for a user

[M. V.]

hello,

I'm using FreeBSD-8.2. I have a program which sends "MD5 
of the new password" of a user to me, and I want to reset user's password with it. I realized I can use "chpass" to set encrypted 
password for a user, but it needs salt and I couldn't make it work 
without it. so I wanted to know:
- can I set user's password in FreeBSD if I have only MD5 of the password? how?

- If answer is no, does anyone know how "salt" is being used in FreeBSD 
crypt for encryption? is it a simple concatenation,etc or it's more 
complex than that?

thank you.