Subject/To rewrite

Hi there

Can anyone tell how to do the following:

If the "From" user is joel, and the message is going "To" sms.co.za,
send the message to test(_at_)sms(_dot_)co(_dot_)za with the Subject being what 
was
originally the user part of the destination address.

EG.

From: joel
To:   12345(_at_)sms(_dot_)co(_dot_)za

would become

From: joel
To: test(_at_)sms(_dot_)co(_dot_)za
Subject: 12345


Is the possible with procmail ?
Thanks
Joel