Automated TNT Cannon Help

I need some help mainly with coding turltes. I am doing as much research as I can but would like to speed things along with this project as I have many planned for CC. My goal is to automate a TNT cannon using turtles to reload it. I have figured out all but this part of it.

Needs:
I need either one or many turtles to walk forward say 5 blocks and then place TNT in the right spots then move back so they are not blown away. This all needs to be done throught rednet so I can control it all with one terminal on the control/obsrvation deck.

Any help, tips, or guidance tward my goal is much appreciated.

well firstly I wouldn't worry about moving the turtle away, just make him place the TNT higher up so when it is activated it falls down to a safe distance, now all you need is a placing code and in order for us to assist you we will need to know how you want it placed

PS: placing the TNT higher up is actually almost essential in effective TNT cannons as you can then place wires etc to activate the TNT without it getting blown up

Wow this is such a epic idea… i must do this!

The general concept is fairly simple. Give all the turtles the same loading programs similar to this:

while true do
  id, msg = rednet.receive()
  if msg == "loadcommand" and id == <id of pc> then -- replace loadcommand with the command you are using.
    load()
  end
end

then make a load() function in the same programs, then set them up how you would like.