Do you know of any ready-made tool that successfully does what you are looking for? if so, see if it works in your setup, and if it is open-sourced, have a look at the code to see how did they do it.
If not, then I guess the only way left is to talk to the sys/net/security admins to see if they are blocking ICMP, and if so, ask them to remove it for a little while just for your testing - assuming you aren't the admin ofcourse
Otherwise, sorry, I don't know how this could be done. Maybe someone else reading this can help.