To have a program to "type" a username/password for me. How?

[kitepilot at kitepilot.com]

To have a program to "type" a password for me. How?
Hello widespread wisdom... 

I want to propagate public keys to several dozens of puters so I can login 
passwordless. 

I am not looking forward to typing (or cut'n pasting) a password a gazillion 
times.  They all have the same username/password combination. 

I know that expect can be used to "type" a password (or to fool passwd to 
change a password without manual intervention), but I don't know how. 

What I want is ti fire a loop to copy my keys to all the machines and to 
have the program to "type" the username and the password to free me up from 
the dull stuff. 

This *HAS* to be possible, does anybody know how?
Thanks!   :)
ET 

PS: No, I haven't researched this, this question is the beginning of my 
research...