I've had a few fun and games getting Backburner to work recently using Lehm's script above, here's what I came up with a few changes.
cmdjob -jobname:"Job_Name" -manager manager_machine_network_name -timeout 300 -workPath:"C:\Program Files\Planetside Software\Terragen 4" -tp_start:600 -numTasks:291 -taskname:1 tgdcli -p "location\scene.tgd" -o location\shot_.%4tp1.tif -ox location\shot_.IMAGETYPE.%4tp1.exr -r -f %4tp1 -hide -exit
Parts in red are things you need to set up, like filename and location, but I also needed to specify the frame range, so -tp_start:600 is telling backburner to start at this frame number and -numtasks:291 is saying render 291 frames from 600, so last frame is 890.
What really threw me was the timeout switch. Backburner defaults to 60mins, so if you have a long render, it will cut out after an hour and re-assign a new task number to that machine and you will never get a frame rendered.
I'm not sure what -hide does in this context, it would be nice to see a frame being rendered, but don't think this has anything to do with that.
Seeing the number of views to this thread, it seems that a few people have tried or trying this, and hopefully some of the above may help.
Best
Jon