1) Just create a text file and put in the following

from: blabla@domain.com
to: Recipient@domain.com
subject: pick up folder test
This is the body

2)Then save the file as EML file extension
3)stop the transport sevrice
4)copy and paste the file to the pickup folder
If you hold contol-v it will paste it constantly, then just monitor the folder item count until it's pastes it to the amount of messages you want to queue

More information on http://support.microsoft.com/kb/297700


Thanks to my colleague and buddy Ed Bringas (former US Escalation Engineer, now Canadian Senior PFE) for this other tip !