Scripted SFTP command line file transfer Mac OS X

I'm working with someone who's been doing simulations on various computers and FTPing the results to a website using a script and the basic mac ftp command basically something like (this is not exact just what i remember from when i last looked at it) ftp -i username@host password cd /dir/ put file 1 put file 2 ... and so on... I need to upgrade this process to use SFTP for security purposes, but there's no way that I can tell to put the password in a single line script for the SFTP program that's built into mac OS X. Is there some other way to do this? I tried using something called LFTP which seemed to connect to the server but the files would always stay at 0% when they were trying to transfer. Any help would be appreciated.