Trying to change Subject: line

I'd like to have an auto-reply that, among other things, changes the 
subject line.  The code for the auto-reply is:


{
   FROM=`formail -rx To:`

(remainder of script goes here...)

}


What do I need to do to get change the Subject: line to something I 
choose?  

Greg
batchman(_at_)dsp(_dot_)net