Can I Use ALTER LOGIN In A Stored Procedure???

Can the ALTER USER statement be used (without a hack like using EXEC) in a stored procedure? I know that the sp_password system stored procedure can not be. Additionally, it is being deprecated anyway. I guess what is boggling me about my attempts so far relate to the errors I am getting due to the user being specified not being in quotes in the syntax. All of the searching I have done so far have come up lame so far; the only examples I have found about it were in scripts that create other scripts for transferring users and other administrative tasks that would be run from the query window, but not from an application. To be complete as possible, here is an example of a script the returns errors:

ALTER PROC [dbo].[lbxChangePassword]
(
@loginid nvarchar(180),
@oldpassword nvarchar(40),
@newpassword nvarchar(40)
) AS BEGIN

IF @oldpassword = (SELECT password FROM contacts WHERE loginid = @loginid)
BEGIN
BEGIN TRANSACTION
UPDATE contacts
SET password = @newpassword
WHERE loginid = @loginid

ALTER LOGIN @loginid WITH PASSWORD=@newpassword OLD_PASSWORD=@oldpassword
END
ELSE
BEGIN
RAISERROR(N'The password you entered does not match your current password.', 16, 1)
RETURN
END

IF @@ERROR <> 0
BEGIN
RAISERROR(N'There was an error creating your new password.', 16, 1)
RETURN
END

COMMIT TRANSACTION

END


************
This returns:

Msg 102, Level 15, State 1, Procedure lbxChangePassword, Line 15
Incorrect syntax near '@loginid'.
Msg 319, Level 15, State 1, Procedure lbxChangePassword, Line 15
Incorrect syntax near the keyword 'with'. If this statement is a common table expression or an xmlnamespaces clause, the previous statement must be terminated with a semicolon.
************

If ALTER LOGIN isn't how to change the password, then please tell me what the correct practice of changing a password is. I want to use the CURRENT_USER keyword in my queries and want I can't finish setting that up until I have this resolved because users will need to change their own passwords through the application I am developing.