Hmm ... ivcon IS the command to launch. What you seems to do is running directly ivcon from the explorer and then enter your "command" (which is a shell command, not a ivcon command).
The correct way to do all this is to:
- open a command line (cmd)
- go into the correct directory (cd ...)
... and then enter "ivcon.exe concflr.3ds concflr.tri" to run the application with its arguments ...
Another usage seems to be (I just tried it very quickly):
- launch directly ivcon (as you seems to do it currently)
- enter "< concflr.3ds" to read your file (it should ask you textures)
- and then enter "> concflr.tri" to export the tri file.
PS: you should use copy/paste instead of huge pictures

(see the contextual menu of the window)