Msg replacement in SMSC

Hello there, since I don't know if this message has been already posted to the mailing-list, I have to send it again. In case you have already received it, please, ignore. 

I would like to be able to replace an sms that is buffered in the smsc, through kannel. To do this, I will need to get back the message id of the sms when I am sending the message (with sendsms) and then send a replace request of the particular message id. 
Has anyone else done this before? Any suggestions where I should start looking in the Kannel source code to make the modifications needed?
Thanks in Advance,
George