You cannot do that.
First of, the password is hashed on the server, so you cannot get it in plain text.
Next, if hi forgot the password, how would he be able to logon and change the password ???? hi cant, thats whats admins are for.
BUT you could have a static user with the ability to call the ALTER LOGIN
] but i dont recomment it ;)
Hope thats what you where looking for ;)