Put this in the "Init" field of a unit or in the "On Act" area in a waypoint/trigger.
Unitname fire "pipebombmuzzle"
The unit will set a satchel charge.
Unitname action ["TOUCHOFF", Unitname]
The unit will set off the satchel charge.
Make sure the unit you have selected to do this has satchels already in his inventory, otherwise this will not work.